Too be honest, speed isn't the problem and isn't as big as it gets made out to be.
Honestly. I bet Brawl would be better received if it didn't have Hitstun Cancel and had Momentum but kept it's current speed. I think, this is all speculation here, momentum was removed from Brawl because of the E3 demo it had, where momentum still existed and people who played it found alternative forms of Wavedashing/Wavelanding. And I'm pretty sure Hitstun Cancel was unintentional, but it still hurt the combo game of Brawl by making them only possibly at low percents.
To put it bluntly, Hitstun that isn't cancelable and Momentum are more important to the game then speed is.