Can anyone tell me why Blu-ray players have to be 430mm wide?

Normal set-top boxes, like the Duo and my Virgin V+ box, are around 380mm. Blu-ray players seem to have got thinner over the last couple of years, but I can't find any that have got less wide - they are all 430mm

I have a nice cabinet below my TV to hold 3 boxes, but the Blu-ray player doesn't fit

Can anyone recommend any smaller Blu-ray players?

I know a PS3 will do the job, but I've got a Wii and preferably don't want a PS3 (or to change the cabinet!).

Thanks.