How can you not have multichannel system

[Captain's Log] We're fast approaching the planet Vinylphilia where the inhabitants, Vinylphiliacs are reporting a crisis with its turntables suffering from unstable platter rotation. [Capt Kirk to Spock] Are we closer to a solution? [Spock], no, captain, but I have been running simulations of the problem on Ensign Smuck's system, and I believe it is related to the 'Fremer' affect where speakers not costing at least $20000 a pair can produce instability among lower priced equipment . . . [Kirk to Scotty] I need full warp speed . . . We need to reach Vinylphilia before their turntables suffer catastrophic failure, and the inhabitants will have to use back up cd players. Perish the thought.

I have not had the opportunity to listen to a really good multichannel system/setup with music as the predominant medium. I've heard some pretty darned impressive multichannel systems featuring DVD movie format. Additionally, I only have a two-channel system. This is my disclaimer - since the hostiles are a bit ramped up here.
That being said, I have always been of the impression that two-channel audio, for music, presents the most realistic soundstage, including the best centralized imaging capabilities. I would not be surprised however, if advancements in technology will (or possibly already have) change the proverbial playing field, or at least offer legitimate alternatives. When multichannel gets it right, does it merely provide a realistic “concert hall” experience, or does it also capture the essence of the performance – sans reverb, room acoustics and atmosphere? Just what is mixed into the other channels? The stage is always coming at you from in front of your position. Certainly, a multichannel mix does not include any instruments/vocals coming from anywhere other than the front – right???? So, what is being channeled to the other channels - reverb, crowd noise…what? What am I missing here?
I heard a multichannel Black Crows DVD at the local Best Buy and found it laughable to hear the guitar coming from the rear channel. I’m sure it was a bad mix, and for certain it was….well, it was a Best Buy system. Anyway, in defining the differences between two-channel and multichannel, just what are some of the more significant characteristics/qualities of one format over the other? I mean in addition to the whole horse drawn carriage analogy and Reggie Jackson quote - which is over my head!

This is great stuff!

2chnlben...The idea that performers should always be in front of you does not reflect the reality of a jazz jam session or a chamber music performance in your home. Note also my earlier posting about antiphonal music. Ambience is not the only sound for surround channels.