Macs have their place. Personally, I prefer Macs in the studio because they are more or less silent, and run very cheaply compared to a PC of equivalent speed, handy when you may need to leave the computers on 24/7.
Admittedly, there are silent setups for PC, but I tend to find Macs' support of music generation in general is superior to PCs.
I suppose it's the right tool for the right job syndrome. I like my PC, it's easy to use, despite common rumour, there's very few problems with the system that haven't been a result of my own tweaking or nosying about, I'd say more crashes are caused by my video drivers than by my operating system these days, and the PC will run my games quite happily.
In a way, this is Mac biting back for the PC's slow rumble into what has traditionally been a 'Mac' market, Music, CAD etc, but it's an inevitable thing to happen, with home production on the rise, people don't want to buy a different computer to make music or graphics on, and since the PC is the most commonly available, and the most flexible from a family point of view, it gets chosen.