There is literally nothing in Smash 4 which is closer to melee, than it is to brawl.
Speed, lag, edges, hitstun, momentum while jumping, dashing. Its all brawl mechanics. I truly dont understand why people say smash 4 is its own unique game different to melee and brawl.
I feel like you could undermine a game's entire existence as a glorified, graphically updated, padded out roster version of Brawl like how PM is basically a glorified, nostalgia-ridden, graphically updated, padded put roster of Melee and is Melee 2.0.
Then again, all sequels are just glorified extensions of the original game. It's all about capturing that profit they once had. Old has-beens trying to make money while never-wases can't do ****, but attempt to fix things and prove something was changed for the better.
What is different? Melee and brawl were polar opposite and smash 4 doesnt sit in between them, its directly next to brawl. IMO of course, I just dont see it.
Besides the obvious of random tripping and ledge mechanics, how aerials and throws work. Aerials are a larger commitment for most if not all the cast minus some characters like Sheik and... Sheik. Aerials being a larger commitment mirror "traditional" fighting games like Street Fighter which also explains Ryu's inertia in the air. This unfortunately wasn't as balanced well, especially at launch and because Smash has a strong air game compared to "traditional" fighting games. Air games defined certain characters like Marth and Wolf while some relied on one or few good to borderline broken aerials like Falco and his Dair.
Throws, well, they're homogenized and generic in Smash 4. Almost everyone uses D-throw to combo, B-throw to kill, U-throw to put your opponent in the air, and F-throw's just there. Few characters actually deviate from this boring design. Seriously, it's lazy design as it basically destroys any uniqueness a throw can be for a character. Anyway, chain-grabbing's gone, so there's that, but characters can grab reset which is just chain-grabbing, but more difficult.
Projectiles are strong like in most games, but Smash 4's weaker when you don't have low end lag or auto-canceling on Fox, Falco, and Snake's older projectiles. Fox's was the least annoying, but still a strong tool compared to now where it's a major commitment to land a 3% to 1% laser that does no hit stun, Falco's was the most notorious as he could effectively control the entire stage, ground and air, and wall you out entirely. Not even Sheik can do that in Smash 4. And Snake? Grenades controlled the stage and could catch angles few characters can ever dream of. It's projectiles that are better than the rest that shine like Sheik's Needles or Luigi's Fireballs and make a strong impact on gameplay, but not enough to invalidate a character's options like Brawl Falco's.
Commitment is huge in this game, but it's "stupid" in a sense that since moves do little shield stun or push in this game, practically nothing is safe unless you're Sheik. That change makes it so few characters can actually pressure shields without being massively punished not to mention the end lag on moves. When Wolf comes back, his Bair probably won't be as strong of a poke as it was in Brawl. It'd be like Fox's Bair at best. Sheik is the only character with a notable poke tool, but it's pitifully weak when it comes to damaging shields. It's what comes next that people will fear from her.
Speaking of commitment, edgeguarding, which I don't see much is now a commitment, but nobody commits to edgeguarding. You have to ensure people die or know for a fact they were gimped. Ledge-hogging doesn't exist, but ledge trumping does. It's a more major commitment to go out there and finish the kill instead of hitting them off and hoping your timing was right for the ledge or that their recovery is going to fail.