Bloody hell, 1999 and 2000 were awesome. What the fuck happened with the industry since then?!
Multiple factors.
Xbox and especially Xbox 360 enticed PC developers to focus on cross compatibility, and therefore non-exclusivity, the byproduct being PC game design devolved towards a less enlightened demographic.
Budgets skyrocketed to continuously attract the spectacle addicted masses, making publishers wary to risk game design outside a very rigidly defined set of genres. This is why the 7th gen is awash in cover shooters and FPS. Smaller studios that tried to be more experimental often didn't break even, and either collapsed or were bought up and dissolved by mega publishers.
The
No Gamer Left Behind movement began in earnest during the 7th gen also, meaning most games leaned towards being piss easy cakewalks designed to make the player feel like a super hero, regardless of actual skill level. This lower bar for difficulty further restricted the types of games that would be developed, in order to cater adequately to average joe dipshit and his delicious disposable income.
Developers / publishers realized they could sell half-finished games to idiots and still make plenty of bank. Hence episodic gaming and huge chunks of what-should-have-already-been-there being sold as DLC. When you're developing a game piecemeal, with no true impetus to ever finish or polish the final complete product, of course that impacts the quality of the game and its holistic design.
Game development tools are now easier and more readily available then ever before. In theory this sounds nice, more people can make more games! But in reality it kind of sucks. The reason is, with so many constant releases (especially indie releases) the signal-to-noise ratio is more off-kilter than it's ever been before. It's extremely difficult to keep up with all the various releases across so many platforms, and know what's truly worth your time. For the consumer it's the whole
paradox of choice thing. Even worse for the rare developer who does produce an awesome game, but is drowned out by the tidal wave of fly by night shit-tier releases every week.
Also special snowflake millennials / libtards assing up game design in general these days. (Can I please just play your game without you shoving your political agenda up my ass every five minutes?!) Ugh, I'll stop there and not even go off on that rant.
There are plenty of other reasons too, but 'eh fuck it.