Speaking as a fairly serious indie dev who's got a non-gamedev day job, actually having it as your day job tends to destroy most of the things that would make it desirable as a career.

If you're AAA, the obvious problem is one of agency - just like being "guy #4968 who worked on Michael Bay's Transformers 5", you … basically have no influence on anything meaningful about the work - you generally have no voting rights to affect the gameplay, or the storytelling or the balance, or just about anything you'd care about as a gamer looking in from the outside. You're just a machine that produces assets (the vast bulk of coders working on those games tend to be scripting together content, whether it's shaders or level scripting).

But if you're not AAA, and it's your job, there's an equally bitter compromise: you have to make a living. There is a significant overlap between the venn diagram of "doing truly excellent work" and "making a decent ROI", but there's a reasonably significant area where they don't overlap. More importantly - I think the most meaningful questions lie smack dab in that area that doesn't overlap, because that's always the part that gets axed in the interests of expedience.

In order to even approach most of the interesting questions in gamedev (whether they're questions of gameplay design, storytelling, balance, etc, etc), you have to essentially start with a full, finished game, and iterate on what's flawed about that title to try and push it from mediocrity into excellence. Many devs do this by making spiritual successors to games they love; some do it by making their own game, and then iterating from there. RAD/Prototyping can "short circuit" an answer to some questions, but we're at a point in the industry where most of that low-hanging fruit has been harvested, and if you really want to make any progress, then the point at which you've finished a 1.0 of a game isn't the "finish line", but rather, is just when you're really getting started. Even if you're making a "spiritual successor" that tries to make something better by tweaking the recipe, that's still your first experiment - now it's time to drive the car you just built around, and learn what works and what doesn't.

But this absolutely trainwrecks right into the typical economic model for a "we're actually making a living off this" gamedev - except in rare cases with new revenue models, that point right there is precisely the point at which you've got to tie off that existing game, call it done, and move on to a new one. If you quit right there, you don't really learn anything - you just make a series of mediocre games (or occasionally, a lucky good one), but you never really understand why they're good or bad, because you're too busy churning out new ones every couple of years to experiment with reworks.

Almost all of the truly great games we've got going right now are cases where there's been such incestuous cross-pollination that multiple studios have essentially done this to each other (major genre titles like FPSes, fighting games, etc), or are small indie developers who've just knuckled down on one "crazy idea" and churned on it for like 10-15 years (minecraft, dwarf fortress, etc). There are other examples like the Civ series, where the devs have essentially made "the same" game 6 times in a row, letting them iterate massively on the formula.

Furthermore, the brutality of having to make a living off of it really hurts friendships - game development is an absolutely savage industry, financially, and chances are perhaps 90% that you're just not going to stay above water as a business. It takes some extraordinary friends to hang together in the face of that. If you're at all human, people will get scared and lash out at each other for not putting their backs into the oars, at least, once it's pretty clear you're not going to make it. Losing the friends who you went into the thing, with, is bitter as hell (I narrowly dodged it, but it scared the daylights out of me).