Wait...what? How do you get that impression?
To me Melee...
I struggle seeing there being less polish with melee than with brawl. Give me some examples of what you mean pls, i'd like to understand your point better.
-Clunky movement: Ok, i kinda get this bit. Melee feels a bit clunky (it just requires more precision, but i can relate to that feeling clunky) if you come from Brawl with its very loose inputs (due to a
10f buffer on almost everything, on/off shields compared to the variable ones from melee and lower leniency for a lot of things using the analog stick).
-Clunky mechanics: Melee's mechanics are more intuitive in every way. Dash momentum carries over into jumps (like in every game apart from brawl[and smash4 apparently]), you don't suddenly appear above the ledge to fall onto it when approching it from below, you cannot cancel hitstun.
-Glitches and exploits: Soul Stunner, Super Wave Dash, Black Hole and the Yo-Yo glitch are hugely situational. Wobbling is probably the only proper exploit (hand offs seem to be fair in Sakurai's mind, since they returned in brawl in full force). Wavedashing isn't a glitch or an exploit (this is debatable since "exploit" is a quite variable term). Your character sliding when airdodging into the ground was fully intentional. Sakurai just couldn't see the potential of it. Brawl is more glitchy and exploity by a long shot (Laser Locks, guaranteed Chain Grabs (there were a few CGs in melee, but you had to read the opponent between grabs [marth's up throw chain vs. spacies for example]), and planking are all exploits that have a truly major influence on the gameplay. Wavedashing doesn't even compare to those.
Sakurai very intentionally designed melee to be melee. He didn't have a competitive scene in his vision, but the game was shipped as close to what he wanted it to be back then. He had a change of heart somewhere inbetween and decided to design brawl specifically
against competitive play (which didn't work because competition is inherent to such a game). Also maybe what Sakurai wants isn't what is best. He's a bit weird.
I ask you this: Did you not have huge fun with both melee and brawl? What made brawl more enjoyable for you? Was it the systems? Probably not. It was characters and music and graphics and more modes (for the most part).
Melee allowed for casuals (oh how i loathe that term) to be casuals and competitive people to be competitive in an incredible fashion. You have so many options. It's amazing to watch, fast, aggressive and technical, while still being so very simple at it's basic level.
Most competitive players just want a new game that recaptures that spirit and is well balanced at the top level (the only place where balance matters if your systems aren't busted from the start) and full of new stuff with support from the developer and a booming scene as a resulty.
Smash 4 seemed (it's not final yet, we'll see) to basically be brawl (a systemically broken game) with band aid fixes to some problems (new ledge mechanics, massive end lag on throws to name some).