New Super Mario Bros. 2

[TomGuycott]

I think the main problem in terms of boss difficulty is that these games are trying to appeal to a rather broad demographic of both kids and adults who played these games AS kids. If they heavily ramped up the difficulty, it wouldn't be as much fun to play for younger audiences, and they might lose appeal in that regard. I do remember Mario games when I was younger and having a bit of difficulty with bosses that as an adult were almost painfully easy.

Then again, there are still some bosses I choke up on as an adult. I can't remember them off hand though... I think it's high time I replayed some classic games. xD