i see no point in an ssd when it will be on sata I or II most likely and terrible controllers that will gain nothing from the ssd. Plus, with TRIM it will kill the ssd slowly and you won't have nearly as much storage for the money using an ssd
I agree with with you with the speed and space arguments.
However, I think meant to say 'without TRIM it will kill the SSD slowly' - in which case, I don't agree. Sure, TRIM helps to keep your SSD working well, but not having it is not the end of the world, and not having it is certainly not going to render the SSD dead in a few years time.
I think the only reason you'd stick an SSD in something like an Xbox is because generally they're more reliable than hard drives (though that being said, I've had one SSD fail on me, but I guess I got unlucky since I've not heard that anybody has had any SSDs die on them), so in theory your games are more protected from disk-related failures. However, the space is kind of limited. 1TB and 2TB hard drives are cheap - 128GB and 256GB SSDs are getting cheaper, but any larger than 256GB and you'll feel your wallet going flatter.
I reckon you might be able to put an SSD into a 360 though. Looks like Nev managed to put an SSD into his PS3. Completely different platform I know, but it could work.