Having only read some of the posts, I apologize if this has been said above.
But, Isn't stereo's intrinsic flaw that if you move from the sweet spot, the illusion of imaging disappears. Therefore, having a firmly roots center channel for voice and to complement the front section allows the listener more flexibility when it comes to reproducing a believable soundstage.
A purist may claim that the other speakers get in the way. I think that some purists are a little hung up on the "magic" of the stereo image illusion (I admit that I am hung up on this) kind of as a party trick. It's neat to "hear" a voice coming from in between my speakers, even though I nkow that no soudn is actually "coming" from there.
Also, I believe in the 5.1 and 7.1 for movies idea 100%. There's only so much that 2 speakers can do to "fake" an "illusion" of an enveloping surround experience. And again, the tricks fades quite quickly if you move around or are not in the prime spot. 5.1 and 7.1 are really neat "tricks" in themselves, but they hold up better than stereo.
Lastly, I rarely am able to sit and listen to music critically. More often than not, I move around and listen to music whiel cleaning, cooking, talking with friends, etc. I enjoy the 7 channel stereo mode during these times because the sound really fills the room. Any effect caused by a perfectly reproduced stereo sound is lost on me durign those times.
