i think there's good and bad,,, and they serve different functions. some are just novelty toys, and others are more story oriented and come with lore. i prefer making my own characters, but when i do shop around, i usually try to pick cs that have an associated arpg group on deviantart. most of my cs are acquired so i can join in with my best friend, who loves those. a few i just find the lore interesting and it's a way to play in that sandbox.
interestingly, sometimes the unintended aspect overtakes the creator's intent,,, with browbirds, for instance, they're pretty lore-rich and have detailed fantasy designs, but the big ones that get bought up (for sometimes literally thousands of dollars) often get set aside to gather dust as collectibles while the owners pay more attention to their myos, which i think says something about the appeal of specificity versus the appeal of personal control. so where browbirds are made to be playable and interesting, they're more just collectibles haha .... really pricey ones. but it sets a high bar for entry, so people with less money and more interest in using them as characters are left out in the cold. any effort to even point out the financial disparity with species like these is met with vitriol, which i suppose is to be expected when you've pumped rent-money-level amounts into your collection.
(as an aside - while i'm happy that popular adopt artists can make good money off their work, and wouldn't mind making that sort of money myself, it drives me up the wall if someone defends their income with claims of 'that's what professional character designers get paid' - i promise the amount of thought and work that goes into designing characters professionally does NOT go into adopts lol. give me your silhouette lineups and texture plans, pull up detailed turnarounds, draw up a style guide, and show me movement tests if you want to argue that. otherwise, be honest and explain it's branding.)
overall i think its as much a money game as it is anything else. some are heinously priced based on name brand over any semblance of quality lol,,, but i think theres a huge oversaturation of them? everyone and their mother has a cs, and most of them are lame--not to put people down, but its just statistically true. there's a sort of 'safe zone' i consider most cs to fall into, with usually four limbs, a tail, maybe some sort of wings or similar extra bit, patterned body, and a fairly cute/cool/otherwise appealing face.... baby proportions on four-legged cs is extra popular. there's even the hyper-safe zone of anime kemonomimi adopts, which are junk like "this anime boy's ears and tail have x pattern on them, $500 please". no offense to people who are into those, to each their own, but personally i find those the least appealing.
my point is, most things fall into that general safe area, which leaves room for only so many combinations - you can slap anything onto that format and call it a CS, but that doesn't mean it's a good idea, or really interesting. there's cs that look like other cs, and some cs that are so vague with what makes them special (or so highly variable, or both) that are difficult to identify as cs when you're looking at them out of context. i've actually mistakenly bought or traded for a few like that!? usually those are highly lore-dependent which is a bit of a turnoff to me when i find out.
overall i don't think they're inherently good or evil. it's a neutral concept that can create playgrounds or hellholes or both, depending on how it's handled, and considering we're all amateurs at the wheel i don't think expecting flawless performance is reasonable.