I think it depends on the area...in Philadelphia, many stages people used 4x12s, so I got one. On a gig in NY, I suddenly felt ridiculous as all the bands used 2x12, 1x12 and the stages weren't really big enough for more.
In the end, even on a big stage, you're not using enough volume to warrant the 4x12, as the engineer will beat your volume down. At that point, it's all for show.
4x12 great at practice though, when you're not being miked up and you can blast away 8)