Thank you for taking the time to give a thorough explanation 
According to any sort of consensus numbers I’ve seen, there are actually (a lot) more Alliance than Horde.
It’s pretty well known that queue times for Horde are longer than queue times for Alliance. Whether long or short queue times is good or bad is debatable, and perhaps a personal preference.
Perhaps. Still many people solo queue on both sides. Many group queue. I’m not sure what the point here is. “It removed the incentive to PvP solo for horde” - what is “it” in this context?
Perhaps the biggest difference here is the macro system! (NOBODY is nor has complained about the macro system).
Not quite. The TBC version of AV started from 2.0, not 1.12.
Some of the changes that happened to AV starting from 2.0 are linked to in a post I made earlier today (linked here for your convenience):
Spell batching supposedly exists in Retail right now and has always existed.
Equally for everybody? Or is there something about it that gives advantages to some people/classes/etc.?
“the current system” could be better defined here. From some of the forum posts, it doesn’t seem that you are alone in thinking this (though whether that is true to Vanilla or not could be debatable).
Fair enough. Thank you for sharing your thoughts thus far