There's a lot of Xbox ports that are missing post-processing effects because the PS2 and Xbox did them completely differently I assume because the Xbox had actual shaders. So they'd do it for the PS2 version and then when porting up to the Xbox just forget about it because it's a quick port cashgrab anyway.
Stuff like motion blurs, depth of field, or haze effects or rain/blizzards or whatever that was done on the PS2 by basically overlaying it onto the frame. You couldn't do it the same way for whatever reason on the Xbox so games will just be missing it or it'll be way toned down. The recent DFRetro episode on Metal Gear Solid 2 noted a bunch of these but he didn't seem to know why.
The Xbox actually has an oddly large number of situations where it's bandwidth constrained and the PS2's fillrate just blows past it, much like the N64's tiny texture cache and the latency on its RAM hobbling it, I want to say it's the related to the shared RAM not being fast enough to keep the GPU supplied. That's why the 360 and Xbone have that tiny bit of on-die RAM.
I have to imagine a lot of multiplat devs were unintentionally just brute forcing PS2 routines with the faster clocks rather than really taking advantage of the Xbox. Basically just trying to get PS2 parity. And then some nut comes along and gets Doom 3 or Half-Life 2 working on the Xbox.
Or Unreal Championship II which doesn't really blow you away until you realize what's in the Xbox in terms of a PC equivalent. A Celeron, 64MB (TOTAL) and GeForce 2/3 with some extra stuff in it.
