Currently, Bonus Armor scaling is wack, and speed stacking is a huge issue even in endgame RBGs. I believe these are two of the major negative forces, as far as gameplay goes, in twinking today. That's over simplistic, of course. What contributes to a community falling apart is something for the anthropologists to study, and would make an interesting grad thesis.
...or an informal essay, for that matter...
What worries me is that the things that I thought were only twink problems, seem to be as bad, if not worse in endgame. The top teams in RBGs flyhack and DDoS. People get piloted to glad. These are obviously player issues, but I think if people thought Blizzard took pvp seriously, maybe they would too. Blizzard has the opportunity to set the tone for the game. Players actually do want leadership from the designers, but the tone they seem to be setting is ineptitude and uncaring. I don't think it has always been this way. I think a big part of the reason people are giving up on WoW pvp, is that they've given up on Blizzard putting as much effort in to balance as they did to playing. They've just had their hearts broken too many times, and gave up.
Blizzard Activision CEO, Bobby Kotick, said he wanted to take the fun out of making games. I think he succeed, and what you have now is people that have the technical skill to make shiny pixels, but lack the vision on how to make a fun game. He stifled creativity, making the workplace unfun. What he didn't realize, or care about, was that fun environment was really part of the benefits package of working at Blizzard, just like the health insurance, or vacation days. Sure, you can eliminate the fun to show to the shareholders that you're a stern taskmaster, but at what cost? He took the fun out of game-making, and drove off the type of people that like to have fun playing and making games.
So, I think what you have now, is basically a bunch of talentless hacks with no vision. Game design, true game design, like the people that invented chess or baseball, is not something you're going to learn those Game Design paper mills that advertise on TV, but those are the people that blizzard has, now that they've ran off creative geniuses that used to work there.
The skill set you need to design a player vs, player game, I think is more related to something like a hockey or basketball coach, someone that can envision player actions and reaction in their mind. Games can be simple and fun, or they can be complex. But they have to be well thought out. I think what Blizzard lacks is someone with the capacity to come up with a vision, in that persons mind, for how the game should actually work, in totality, and the power to carry it out.
My guess, is that they've given the all the controls to the pve design team. I see that as a big mistake because I think it's pvp that sells games. People didn't buy Call of Duty or Madden, for the single player campaigns. People don't get all excited watching videos of 40 man raids. Blizzard once had the imagination of gamers captured; arenas were an e-sport, people wanted to come to wow because it's where the talented gamers were. When Blizzard took their focus off creativity and pvp they shot themselves in the foot. Wow, still has a lot going for it: games toward the end of their cycle can get very fun and balanced, even after they stop producing much content. But Blizzard has a lot going wrong with it, and I blame Bobby Kotick for most of it.