It makes "absolutely no sense" only to those that want to limit themselves to the current state of theatrical playback. If that's your goal (and it's a completely valid one), then you might as well get a 6.1-channel pre-pro (limiting yourself to 3 surrounds: left, right, back) and run everything in THX mode using dipole surrounds to mimic the diffuse surround field you hear at the local cineplex.

For those wanting to go beyond what commercial theatres are capable of, there's 7.1 and (soon) 9.1 and 11.1 systems. With current 7.1 playback, the rear speakers are run in stereo, allowing for smoother pans in the surround field and stereophonic imaging between speakers. Even the best theatrical sound systems can't do that.

If going beyond the limits of commercial cinemas makes "absolutely no sense" to you, then you need not participate. Nothing more complicated than that. Heck, surround sound makes no sense to 2-channel purists (we only have 2 ears, sound only comes from in front of us, etc), so you'll be in good company. If others don't want to limit themselves the way you do, then that's their prerogative (whether it makes sense to you or not).