[resoluteteeth]

It's hard to even imagine this happening now, but it really does seem like it was a smart decision and Howard Phillips was completely correct (based on his gut reaction to playing the Japanese super mario bros 2) about what people did and didn't want, and it definitely does seem like the mario games went in the direction of not being so hard after that, although it's impossible to know if that was the specific reason.

[elihu]

Also, relating to difficult it's interesting that the original game that SMB2 in the U.S. was based on didn't have the B-run ability, and that change made the game substantially easier. Though in that case they may have decided they had to add it in order to be consistent to SMB1, and the decrease in difficulty was just an unintended side-effect. (Also, not having a save feature made the U.S. version a lot harder, so maybe that balances out with adding the run ability.)