Which in GTA3's case would/could have resulted in pretty large cut backs.
Some cutbacks sure, but the extent of that depends on what was being done with memory on PS2.
PS2 didn't work like DC in terms of how it used it's memory, PS2 was built for streaming data constantly rather then keeping everything in RAM/EDRAM.
All consoles that gen were built to stream data. Sega had actually been building devices with data streaming i mind since the M-CD add on.
It's really not true to say that the DC was to "constantly keep everything in RAM". That's a bit of a strange thing to claim tbh.
PS2's DVD drive could fill it's 32MB of RAM in less than 6 seconds which helped push it's streaming nature.
With DC's 1.8MB/s streaming rate from it's GD-ROM drive you're not going to streaming a fat lot and would be forced to store way more in RAM.
It's an over simplification to say that "you're not going to streaming a fat lot and would be forced to store way more in RAM".
"Storing more" isn't your only option. You can stream the same amount but over a longer time (potentially with more fade/pop in or pauses if you go too fast); you can stream less by going lower quality or fewer unique assets; you can stream less by using more highly compressed assets/data;
or you can store more.
But storing more rapidly become problematic in a game with unpredictable movement leading to unpredictable access demand from the optical drive. Storing and/or loading some data in a more compressed format would be useful (VQ textures are naturally small), or fading higher res textures in later, or temporarily having less NPC or vehicle variety in while you load more in.
But the
real problem for streaming from optical where you have unpredictable accesses is access time. Both CD and DVD are pretty terrible in outright terms, often equally terrible tested across the full radius of the readable disk, though with a practical advantage for DVD where higher densitty sotrage allows for faster head seek times. GD-Rom was realtively good in this regard, but I'd guess PS2's DVD is still better. But it's still this that's going to more important than peak linear read speeds.
Access times more than linear read is what made cheap USB drives and cheap USB HDDs so much better than DVD for running Rage off on the X360.
That's due to a limitation with VU1 which only really worked efficiently with certain methods of compression.
That's why adding more modern compression support to the GS wouldn't have really done anything as VU1 would have needed to have been updated/redesigned to perform well with better solutions.
I don't really agree with this. The SH4 on the DC didn't have any particular hardware to handle VQ compressed textures (as far as I've ever seen), but you fed the GPU the texture coords and it could decompress that format of textures on the GPU as it consumed them.
Native support for a texture format (VQ or S3TC or the like) would have allowed higher quality textures to be in VRAM as the GPU was drawing whatever you were having it draw at the time.
What it lacks in texture detail, it makes up for it with a decent amount of texture variety in my opinion.
Not sure I agree, I see a lot of very low colour, low resolution, highly tiled textures on screen. But if you're right, that would make a good argument for PS2 using a good chunk of memory for textures ... which makes the case for a strong (if still cut back) DC port of the game.
And PS2 was held back by lacks of tools and piss poor technical manuals.
At first sure. What didn't hold it back was Sony's resources, developer support, development man hours, years developed for and generations of software developed for it, and PS2 certainly wasn't stuck with 1999 assets and art creation tools for the whole of it's life.
DC was effectively dead by Jan 2001. Nothing beats that in terms of being held back. Having crutches as a child beats being born into poverty, being largely ignored, and then being uethanised as a toddler.
That's why this conversation is so interesting for some of us. Because by and large we know what the PS2, GC, and Xbox could do. We don't know just how far DC games could have progressed - but evidently it's "quite a lot", even if it's not as far as some people wish it could.