Always been the nature of twinks in random BGs. Wargames are where you want to go if you want something resembling a balanced fight with fair opponents. Because you'd be playing with/against your friend group, instead of randoms.
Expecting other people with no other common ground as you (except interest in wow pvp) to have the same approach as you, is a little too much. People are going to gravitate towards the thing that has the highest degree of success in pvp, that has always been the case. At 29, things tend to get a little better for every spec, a main ability/passive/talent opens up by that level that will bolster most classes rotations. It may be a matter of picking what you like and building it to be the strong character you want, rather than picking the perceived 'best class.' At level 20, people would be more inclined to pick from fewer specs that have more rounded toolkits by that level, causing overrepresentation.
Which is the advantage of wargames. You aren't queuing into a random group. You build the teams then fight each other directly. Works for BGs up to 15v15 (haven't ever tried anything bigger, might be possible), and that's how you solve this problem. Anything else Blizzard could do would result in some other undesirable change, pushing some players away from activity. The fact some of us have now migrated to wotlk classic in prep for launch of that, shows how fickle brackets can be.
Until we see something different happen on Blizzard's end, rolling in randoms with a group of people is going to be the only way to ensure you don't get steamrolled by the other team doing the same thing. Naturally, that's what people will gravitate toward. Were doing it before, in this very bracket, so yeah...
.