For me MM7 has a very objective problem which is it's controls. They're just bad, and for a Megaman game that's a huge thing. I still don't get how Capcom didn't realize this before releasing the game. The fact that there are romhacks to fix these problems make it even more evident.
Now MM8 is definitely not perfect but it's more like a matter of whether you want to look at the negative or the positive. Due to nostalgia I prefer to look more at the positive things, which as I already said I like the smooth gameplay, characters animations and the whole mid 90's thing, which to me playing this game is like going back home after a long trip.
Then there are the 8-bit games. I really like their precise and tight gameplay, in other words 'jump and shoot' feels great. But the level design in some of those games show their age, as well as some bosses like the Yellow devil.
Some people will say 'git gud' but I just can't get myself to enjoy unbalanced difficulty. And when I don't even have nostalgia to fill the gaps of bad design, then there's not much left in terms of how much I'm capable of enjoying these games.