Well, it has been said that not every move needs to be particularly useful. In general, uthrow has always been the least useful throws in smash games in terms of combos. Uthrow has generally been used to toss people up and then punish their landing or to just keep juggling them. That or it's a kill throw in rare instances.
uthrow in Melee is godlike.
Fox - up air
Falco - dair, shine, whatever
Puff - REST [or uairs]
Sheik - CGs spacies at 160% [ok it's her dthrow whatever]
Marth - utilt or regrab fastfallers
Peach - CG fastfallers for a while, often leads into nair or bair
Falcon - KNEE
Doc - fair
Ganondorf - same thing as Sheik but w/e
Pikachu - usmash, regrabs, uairs
Samus - combos on spacies and maybe middle fallers as well [Sheik, Doc, etc.]
Luigi - SHORYUKEN [ok that doesn't really work and his dthrow is more useful but it's one of the few uthrow combos that works in Minus]
Mario - fair tech chase, bair
Link - dair, uair, nair, dsmash on fastfallers [dthrow is better vs non-fastfallers tho]
Young Link - see Link
DK - uairs for years, fair
Yoshi - I dunno on him actually, probably uair fastfallers
Zelda - fair/bair depending on DI on fastfallers
Roy - see Marth, gets strong fsmash too on little/no DI
Mewtwo - combos on fastfallers, kills well
GnW - I don't understand his throw game
Ness - combos on spacies
Bowser - combos into fair?
Kirby - his throws except dthrow all suck, but this one does good damage, can't be escaped, and can set up tech chases [sorta]
Pichu - CGs into usmash. uair/nair juggles
Brawl uthrows are admittedly pretty bad, but that's due to lack of hitstun. And also this is Brawl Minus... so I'd think we'd make uthrows not suck [see MK, Pikachu, Luigi, Link, Pokémon Trainer for good uthrows].