Ok. Having not played the game yet, I think Sakurai is trying to punish players for trying to chain an air attack directly into the ground. If you attacked directly into the ground in real life, you would have alot of landing lag because you'd be off balance (presumably, depending on the attack). Sakurai may have done this to prevent the tendency for competitive players to hop like an inch off the ground and flip out aerials as though they were on the ground (which was possible on Melee and I guess 64). To me, that's a fair change. That shit was annoying to me in Melee anyway- here's why:
To me, Smash should be a fighter about strategically maneuvering around a stage. Not about exploiting every frame of information out of a character. This was basically what Smash 64 was. Even now, if you watch 64 competitive play it's much more about exploiting where the character is, rather than who can who can preform the fastest muscle memory move on the controller. Melee is the opposite. Much more focus on exploiting the intricacies of the games controls, and less focus on stage strategy. I don't think this was what Sakurai intended, and he essentially retaliated against the competitive community with Brawl (tripping, Meta-Knight, and so on). Even though he'd never admit it, I'm pretty sure he perceived the competitive community as an elitist undesirable side-effect of the game's success. Why else add tripping? It was essentially a "fuck you!" to the tourney scene.
Brawl, forgiving everything its did wrong, played much more like 64. It was much slower than Melee, and stage positioning was critically important- which is why I loved the stage creator so much (puhleassse bring it back!). Smash 4 may return to this philosophy again (albeit quite a bit faster than Brawl). Long story short, this is not Melee. It's going to be different, and I'm okay with that.