64 is the same level of stupid as Brawl, just taken in the complete opposite direction, so it's more fun. As opposed to almost nothing being safe on block, almost everything is safe on block, and grabs have so little cooldown they're borderline nonpunishable, plus they are both combo starters and kill moves, which is frankly dam* stupid, so shielding is barely an option against somebody who can lag cancel, which is stupid easy. As opposed to few chances to put somebody with good DI in a bad position, brain-dead easy combos that look kind of pretty occasionally come off of mostly safe nonsense with generally good priority. It rewards offense more than Brawl, which rewards defense a bit more than people are comfortable with, but the offense 64 rewards is stupid.
The funny thing is, even with all this its harder to be good in SSB64 than SSBB.
There are combos to practice as opposed to no combos [they're fairly easy but not brain dead easy, you need to be at least a mid competitive level to start doing the good combos], Lag Cancelling, which you say is "stupid easy", is only a little bit easier than Melee. Shorthopping is easy compared to Melee in SSB64, but shorthopping in Brawl is a lot easier.
That grabs being kill moves and combo starters though is false. It depends on the grab, almost no grabs are kill moves AND combo starters unless thrown off the wall. Otherwise, the only ones with combo grabs period are Jigglypuff, Falcon, and probably DK. DK's can kill [fthrow], rest can't unless at insanely high percents.
General faster speed in SSB64 means you need to adapt faster than in Brawl as well. Sure, I admit that Melee is more difficult to be good than 64, but 64 is nothing, NOTHING, like Brawl.
Not to mention that yes, it's more fun. But that's subjective.