It's also worth noting that the VERY FIRST thing many (and, I suspect, most of the modern, decently capitalized) studios look for in a monitor is XLR connectivity. They're set up this way for many reasons (the performance advantages of active, balanced speaker designs being only one of them), including reliability, compatibility, and simple legacy. A lot of the pro speakers out there leave much to be desired sonically, so the ATC (a pretty fine product by any measure) stands even taller in that crowd. IMHO the ATC are excellent products, but choosing a home loudspeaker and a studio monitor are, more often than not, two very different excersizes, unless you use active speakers at home. Not that that's a bad idea - just rare.
There are certain applications where passive monitors do pop up in studios (sometimes on the older consoles) and they can be almost anything.
Marty