CarX Drift racing online is one example. Game looks like shareware trash, cheap and generic but there's a reason this is highly costumer rated, it's an amazing feeling racing game that has an incredible feeling drift mechanic. 

Dust an Elysium Tail looks like a generic Metroid vania, furry game but it is one of the most satisfying 2d metroidvanias that exists. 

Beach buggy Racing might as well look like a mobile game but the fun in it is immense and it's up there with Mario Kart and Crash team racing in gameplay. So much fun.

Cat Quest Looks like a mobile game and in many ways it is, but it's actually really fun and has simple but oddly endearing quests and sstory. It's combat is as basic as it comes bit very fun. 

Death's Door doesn't have the best style, but is quite excellent.

Vanquish is a bit meh in art style and characters but might be the best action game ever crafted.

Dark Souls 2 is generic and lost a lot of atmosphere, however it is grossly underrated and it nothing short of superb.

VanQuish is awesome, such a blast to play and my God does it look like the most generic boring thing if you haven't played it. Such an understed game. 

I really wanna get around to deaths door, it actually does look good. 

Alpha Protocol wasn't much to look at and was kinda janky even for its time but it's one of the best ARPG's (and spy thrillers) of its generation in its own way. One of the games that delivered best on your choices actually mattering.

Never even heard of it, it's no on PS store though...

Bayonetta 3 was ugly by Switch standards, but it was a blast to play.

Sniper Elite 3 looks low budget and uninspired, but has amazingly satisfying tactical action.

Medal of Honor Heroes 2 seems like just another generic WW2 game on the surface, but the smooth and creative controls really elevate it.

VanQuish is one of my favorite games ever but yeah the thought of taking place on an O'Neil Cylinder sounds cool the environments tend to look too similar.

Dragon's Dogma. At first, it does look a bit generic but once you get into the game it works and it sucks you in.

Gungrave GORE. This is an acquired taste and I have been a fan of the series since PS2. It's one of those best played on hard. It's basically a long PS2-era Arcade game like the originals. People see it as shallow but when you see expert players it's not the case. Simple yes. Shallow not so much. Not the best graphically tho the cel shading option to me helps. It's a niche game that appeals to a very specific audience.

Evil West. Not saying it's ugly or generic but it does have a budget look. Thankfully it's a fun game. A callback to the 7th gen B games. A little GoW and Gow but also a beat 'em up in there as well.

Bujingai.  Starring GACKT! Didn't look the best on PS2 but it's a solid action game.

Assault Suit Leynos/Target Earth. Not the best-looking Mega Drive/Genesis game but it's a blast to play. Sequels are better and the remake on PS4 is fantastic. For the time tho Leynos was a unique and fun take on Run n Guns.

Binary Domain. Not the most visually distinct game. Not ugly technically for the era but good-looking. Just artistically not the most interesting. It is a blast to play tho.

Tales of Vesperia. Not that this looked nice as a cel-shaded 7th-generation RPG But to most just another anime JRPG. I don't think too highly of the Tales series but Vesperia is almost an accident in how good it is. Not only is the story good with good characters. It breaks some tropes. From Hero to Villian. Sure it has some of the same tropes and power of friendship. It also doesn't have a naive orphan leading the way but an interesting anti-hero without trying to be overly edgy (ehem Berseria)

REcore on Xbox One. Not a looker. Trailers don't look interesting but it is a fun bargain bin buy. The last act sucks but everything else is a solid game.

Last Bronx and Outlaws of the Lost Dynasty on SEGA Saturn. One is a 3D fighting game and the other is 2D. The in-game models of Last Bronx are not the most interesting but one of the most fun games in the genre on the system. Outlaws of the Lost Dynasty could be confused as a cheap Chinese-themed SF ripoff. The game is quite good. So few know about these gems.

Aliens Fireteam Elite. Not graphically impressive at all. Fun Co-op TPS and the best Aliens game ever made. (notice I said Aliens not Alien)

Bayo 3 was one of my biggest disappointments this generation.  It looked like hot garbage, run poorly and wasn't as good as Bayo 2.  Still a really good game and I enjoyed it.  But lord I hope it gets a S2 port with way better graphics.  Overall, it felt like a step back.  

Since you mentioned Bayo 3, I think Astral Chain fits the bill here.  Very generic looking, at least IMO, but an absolutely amazing experience.  

Bayo 3 did disappoint me a bit, but only in the sense that I went in hoping for an amazing 10/10 and got a very good 8/10 instead. 

It's still probably the most fun I had with a game in 2022 though, just for the insane setpieces, kickass soundtrack and fluid combat. 

I like Viola a lot. Dorky punk rock girl. Then again I have been loving the insertion of punk characters in humor action games for the better part of a decade now. From NMH. Sunset Overdrive. Bayo 3 and more.