I wonder if you were ever actually playing during this period of the game because you are absolutely wrong about this. The whole TM vs. SS thing happened BECAUSE of battlegrounds (specifically AV). When AV came out you had to go to the portal to que (and I bet you don't even know battlegrounds have portals). And given the fact that AV was actually fun back then it was very popular. Since the battles typically lasted multiple days and you could easily lose yourself for hours in there so the que times could take a while. Thus, the Hillsbrad Foothills basically became its own battleground full of people waiting for a battleground. It had nothing to do with ganking lowbies and being a dick (although admittedly there were many casualties). It was actually best practice to AVOID killing lowbies because that would earn you a dishonorable kill. So what killed it?
The next patch when Blizzard added battlemasters that allowed you to que right in your main city. Sure some people still made it out there but it was nothing like it was and never will be again. This is an interesting thing in and of itself because everyone loved going to Hillsbrad for some epic battles yet as soon as Blizzard offered a choice between going out there to que or just simply que from your city.. the players pretty much unanimously chose the city option. Why? Because getting in to AV was the end goal and TM vs. SS was just the in-between stuff between them and the end goal. When Blizzard puts in mechanics that allow you to get to your end goal faster and skip the in-between players pretty much always do it regardless of how much they actually enjoy the in-between stuff (or claim to). And this is the same reason why players don't choose to ground mount when flying mounts are available. Does it make any sense? Not really. But its the reality of it. And completely disregarding reality when designing the game (or doing anything for that matter) is a damn foolish thing to do.
Another reality is that flight does have a negative impact on wpvp (even if it is a minor one compared to other things) but taking flight out is hardly going to resurrect it to its former glory. Nothing probably ever will. I really think its time to just put this argument to rest because it has nothing to do with this discussion on whether or not flying is going to return at some point in the xpac.