My i5 iMac 27" works pretty damn well. I don't have a need for anything else for my music.
For work, I do corporate video and the latest iMacs and macbook pros are plenty fast for video editing in a fast paced corporate environment.
I suspect the era of the tower is over. Computers have just gotten to damn fast. Only fringe users will need more power than in i7 macbook pro or an i7 iMac, and it's hard to justify the development expense for those users. Those users, IMHO, will invariably move to windows PCs. I don't see any other way.
Luckily my video editing software is cross platform, so it's really not a problem at all.