It feels like they were afraid to make him good. I've heard Ult Ridley described as a concession character that's only here out of obligation, and as much as it pains me to say it, I have to agree. He doesn't really feel like Ridley a lot of the time. The times when he does are great! But those moments are few and far in between.
Make him bigger, give him some armor to compensate for the increased hurtbox, give him better specials (other than side because that's good as is), change that atrocious forward air, make his throws more inspired, give him an air game, and I'll be like, YEAH! THAT'S RIDLEY IN SMASH!!
I'm glad we're on the same page as far as wanting Ridley to be improved on, but I don't agree with a lot of this. I don't need him overhauled, I just see the potential to improve on several already existing elements of his kit so he'll feel less awkward and be more of a force to be reckoned with.
I actually like his Fair just fine because a multi-hit stab move fits Ridley quite well, it's fun to carry opponents offstage with and a claw swipe is aping off several existing characters already. His throws could be better, but impaling you with his tail and scraping you across the ground is certainly Ridley. I would hesitate to call them bland, they feel deliberate in their cruelty but they could be pushed further. His specials are fine, I really like his unique fireballs and Down B is one of the most brutal and rewarding moves in the game.
And Ridley DOES have an air game - every aerial except dair is pretty useful. Nair and fair are really solid combo tools, bair is a reliable kill option. His offstage game is really solid, even if his best option is a poke tool. The issue is just that he can stand to fly faster, and that his recovery options are highly telegraphed with only one extra jump to accommodate. His offstage game is good, but he needs to be able to get BACK to the stage. And he needs to be able to chase you down more reliably, there should be nobody more threatening to be in the air with. The fundamentals are here but it can be stronger.
I don't like calling anyone a concession character - more often than not, this is a narrative spread by the people who were wrong about a character and want make excuses about how Sakurai was forced at gunpoint by fans to add them. If Sakurai didn't want to add Ridley, he didn't have to. But given that Ridley has appeared in every game in the series in some capacity or another (okay, not Smash 3DS), I'm gonna go out on a limb and say Sakurai might like him.
The attention to detail given to Ridley is not one that implies a rush job or lack of inspiration. Like you said, they were afraid to make him good, and this is a problem that persists across a majority of the heavyweights on the roster. A fighter who is difficult to KO, has strong combos, has strong kill options, can reliably recover... Ridley has all the tools necessary to be really damn annoying, so I suspect he's a victim of power creep. After DLC it's a lot easier to see how other characters are given unnecessary limitations, and I hope that instead of simply nerfing DLC characters into infinity (although we should do that, too) more work is done to bring existing characters up to speed and not being afraid to give them some of those more threatening tools.
TLDR, I love Ridley. I think he was handled quite well, I just need him to be sufficiently buffed. I don't agree with every moveset decision but I don't find his kit to be disorienting or unfitting, I just want to be able to recover without my options leaving me vulnerable for a hundred years. I'll take some armored attacks too though.