The main reason is disc size. Like you said, GTA 3 (and 4) had to fit on a single DVD, now games have duel layer blu-rays at their disposal. We've seen this with every new format from CDs.
It's not helped when people throw a conniption if they see a texture repeated or a texture that's less than 8k. It makes for good glitch compilations, but it can be hard to tell where sarcasm ends and genuine rage begins.
Yeah, I totally get it that visual fidelity expectations have gone up and that requires more space, but there's still a lot of room for savings that developers just don't seem to care about anymore.
Audio comes to mind. Developers seem to be shipping audio completely uncompressed these days -- music, dialogue, sound effects, everything. And for games with lots of dialogue, they include all the audio for every translation. That inclusion is obviously necessary for an on-disc game, but for an online game, it's pretty silly when each language can be made a separate free DLC.
Using uncompressed audio is inexcusable, though. I've seen games that have 5+ GB just in uncompressed audio. Even using 320kbps high-quality MP3 compression, that can easily be reduced to under 1GB. We've had good high-speed MP3 decoders for 20 years now. Today, it's essentially free in terms of CPU resource consumption and it reduces disk I/O and storage space by a factor of up to 10x. Ogg Vorbis has similar performance and is open-source and royalty/patent free, so that isn't a concern either. There's AAC as well, but there's licensing fees involved in using it commercially.
Uncompressed textures and other graphics assets are silly too IMHO. Practically every graphics card manufactured in the last 10 years has supported compressed textures in all sorts of formats. They take up less space on disk, require less memory on loading and transfer faster to the GPU, which keeps them in compressed form in VRAM, decompressing them on-the-fly during texture lookups. The decompressed texture is never stored in memory anywhere; it's all done on-the-fly by the hardware, and to my knowledge there is no performance penalty for this as it's handled by the shaders.
As with audio compression, there's a wide variety of texture compression standards supported by modern hardware and there are free/open-source compression tools available. The only downside, of course, is that it takes longer to "bake" texture assets since they have to be compressed in the pipeline. There are hardware-based compressors that can accelerate the process though. And the game engine needs
to support compressed textures as well, but practically all of them do.
I just don't buy the argument anymore that compressing game resources has an in-game performance penalty. The hardware is too good now (even on the consoles) for it to be a problem these days. I'll grant that decompression is not always a zero cost operation, but it's an
extraordinarily low cost operation that either only has to happen once per resource or can be done in hardware at no extra cost.
There's other bits of silliness too from lazy developers, like including alpha channels on textures that don't need them, making textures too large (you really don't need an 8k texture for that distant mountain range the player can never reach, I promise) and not using engine and hardware features to add detail instead of trying to cram it into the textures. There's also a tendency to use insanely high-poly models and terrain where it's not needed, especially when techniques like tessellation can add detail at runtime when used correctly. Again, those distant mountains the player can never reach don't really need to be million-poly models when 10k poly models with tessellation will do the job just as well.
I still maintain that developers just aren't using all the techniques at their disposal to reduce game footprints and optimize their games. Maybe it's because they just don't have enough time during development to integrate them, or maybe it's because they've gotten complacent since bandwidth is cheap and so is storage (at least on PCs). It's astonishing though that they're not taking the time to reduce game footprints on the consoles, though.
Just imagine owning a PS5 or Xbox-whatever and only being able to play 6-7 games on demand before running out of space, and having to delete a game to make room for another 100GB+ game that could take hours to download depending on your broadband link. If you've got shitty internet, it could take
days to install a game or download its patches at these sizes. That's just god damn awful. Sure, PC users don't have infinite storage either, but at least they can
add lots of storage as needed, whereas the consoles either don't support expansion storage at all or only offer USB connections for external storage. That's going to be slower than SATA or PCIe/M.2, even if you're using SSDs.
</sperg>
ETA:
consoles already put a lid on that with their limited ram and power.
Nah, compression should be a net gain for consoles, in terms of on-disk footprint, loading times and memory use. See above for an explanation. Modern gaming hardware has more than enough horsepower to decompress game assets on the fly without any noticeable impact on performance. They often have hardware that can handle a lot of that work at no performance cost at all (there's audio/video decoders on every GPU today, for example, that have their own dedicated space on the die -- using them doesn't involve the rest of the GPU so that work can be offloaded for free onto an otherwise idle component).
