First, above said is just an assumption - I already explained memory use is Not the Only possible difference in my previous post.So the amount of memory it relates to is main RAM where you have 32 MB... I find incredible that Square doens't have enough room for textures due to high polygonal models.
Second, it's actually not difficult at all to waste most of that 32MB on everything else but graphics content memory - and some PS2 games have been quite "successfull" at doing that too.
Consider Splinter Cell used 4MB on PS2 and 8MB on XBox for textures Per Level. Which makes it only ~10-12% of available memory in both cases. And rest assured they didn't just leave the remaining 90% free ...