Let's put everything into perspective.
Mega Man 10 bosses are difficult for many gamers because of how they are incorporated into the level and difficulty design of the game. By default you have 3 lives to get to the end of every stage and defeat the boss. There's a checkpoint about half way through the level and just before the boss. It's very unlikely that you'll develop an optimal strategy for beating a boss the very first time you encounter him if you use the M. Buster. This is a nice way of saying you'll probably get a game over at least once per boss. If you lose all of your lives, you have to replay the whole level for another attempt.
When you restart a level the whole process of trial and error becomes disrupted. When the game disrupts the process of taking observations using your reflexes, storing the info in your STM, analyzing the data, and storing the data in your LTM your hard work can be lost. Because STM is temporary, having to switch gears and concentrate on making it through the level again will most likely flush your mind of any data not stored. So, unless you take the time to store everything away properly in your mind (or take notes externally), you'll probably have to relearn a few lessons when you face the boss again. This unfortunate side effect of the difficulty design of Mega Man can greatly prolong the already difficult task of learning and developing strategies.
A key part of the trial and error process is the error part or the feedback/results of the experiment. We can't figure out how to adjust our thinking or strategies if we don't know if something went wrong. This is why sound and visual design goes far beyond aesthetics in game design. Players have to see, hear, and/or feel the feedback to play. This basic idea is a key part of the interactive experience of video games. Unfortunately for Mega Man 10, the NES style of visual and sound design hamper the feedback at times. Because the designers wanted to work within the the limited audio capabilities of the NES, when playing MM10 the sound scape can easily be crowded forcing the game to drop sounds. Sometimes you'll miss important audio cues not because you weren't paying attention, but because they mysteriously drop out. Overall, this issue is a very small part of what makes MM10 so difficult.
On the other hand, MM10 gives players lots of ways to adjust the difficulty of their experience. There are the easy, normal, hard difficulty modes that change the enemy design and level layouts. If you play as Proto Man or Bass, you’ll have a different kind of challenge to face. You can always buy helpful items from the store. And as always, you can use the specific powers to help you progress through levels and defeat bosses with relative ease. Strangely enough, these options don't seem to be enough for many gamers. Aside from MM10's easy mode, many have expressed that MM10's difficulty is hard for the sake of being hard or "cheaply" difficult. And this isn't even referring to MM10's hard mode.
How much “easier” would MM10 be if the developers found a way to simply inform the player of key information? The idea could be as simple as the help system built into New Super Mario Bros. Wii or Super Mario Galaxy 2. If you die enough times at an obstacle the game will offer a hint video showing you how to tackle the challenge. Or Capcom could do it Donkey Kong Jungle Beat style. After beating a level, players are treated with a short video that encourages them to try new and interesting things. Would such measure be enough for most gamers? Or do they lack a certain kind of seriousness in their trial and error methods? In other words, are gamers simply unwilling to buckle down, do some experimenting, learn something, and develop their skills?
A little bit of information would go a long way by sparring the player from having to create as many experiments, test their theories, and update their knowledge base as they go along. But if the developers just told us how to get through a level or how to beat each boss, would that spoil the experience? Mega Man is already a game you can beat in under an hour. Perhaps this difficulty design makes the journey appropriately long, memorable, and satisfying.
I wonder if forming a complete strategy for the MM10 bosses is analogous to solving a puzzle. The given is that each boss is solvable meaning when just using the M. Buster it’s possible to win and take no damage without making any guesses. So coming up with a solution or strategy is a considerable test of one's knowledge skills. If someone told you how to solve a puzzle, not only would the challenge of the puzzle disappear, but, like a spoiled joke or movie plot, there's no way to unlearn what you know. A spoiler like this can ruin an experience forever. Looking at it this way, a hint system seems like the wrong way to go.
Perhaps MM10 bosses are best categorized in two parts. A strategy/puzzle/knowledge based part and an execution/action part. You could argue that even if you know how to perfect a boss you still have to pick up the controller and actually pull it off using your reflex, timing, dexterity, and adaptation skills. However, so many of these facets are greatly supported by knowledge skills. For example, one way to increase your reflex abilities is to reduce the amount of stimuli you're looking out for. By using game knowledge, you can figure out what you need to look out for and what you can ignore. Obviously the acquisition and test of knowledge is a tricky part of education and game design.
So if you’re the kind of gamer who wants to reach that next-level using just your own abilities, what happens when you hit a brick wall? What happens when you’re angry and/or fed up with the game because you can’t figure out the strategy? What do you do when taking a day, week, year long break doesn't make things any easier. Do you blame your skills (or lack thereof), your trial and error process, or should we look to the developers to craft better teaching tools?
It's a good thing Capcom has innovated in this area. If you reach a boss or mini boss in MM10, you’ll have access to play that boss any time from the main menu so you can practice without the steep punishment of having to play through a whole level again. Without this feature, I wouldn’t have developed any complete strategies for the MM10 bosses on the hard difficulty using the M. Buster or any other weapon for that matter. Comparing my experience with MM9 proves this. I played MM9 a lot, but not as much or to the extent as I have MM10.
So in my quest to become Mr. Perfect I’m currently at the beginning of the Wily levels. This means I’ve beaten the first 8 stages and bosses without taking any damage. To get this far I not only had to tap into almost 20 years of Mega Man experience, but I had to constantly remember and understand how the levels created layered challenges, apply my tactics, analyze new challenges, evaluate my strategies based on my goals of perfection, and create a complete strategy for every boss and level challenge. This process of trial and error and high level thinking is what I do all the time whether I’m playing video games, piano, or working out new recipes. So perhaps this is why I don't consider Mega Man 10 to be too hard. Knowledge makes the challenges easy. And even when gaining that knowledge is difficult, once I have it, playing is a breeze.
As for Mega Man 10, I believe I’ll stop my pursuit of perfection. The next 1/3 of the game must be played through entirely without taking damage because I am unable to save and resume progress on the Wily stages. I should add that I've been working on Mr. Perfect with Mega Man on normal mode. I could easily switch to Bass and rock the house on easy mode. It's been a great run, and I learned a lot about how I learn, difficulty, and game design. At 98.5% game completion it's...
GG, MM. GG.