They do, even the man himself, Yoshi, said he's made changes from observing the Japanese servers and their feedback. The last out of touch update of buffing the literal two strongest jobs (BLM and MNK) might have had some influence from NA Streamer community events, however there were also events in Japan and the jobs weren't featured as much as they chose to 'play for fun'.
Blizzard does lots of micro balancing (excluding exploits or bugs they can't be bothered with), they, even back then 2006 and onwards, they would never leave PvP as stale as this game. Outlands was one with the least updates when it comes to PvP, but there were many class balances after arena. However, the rule of thumb is Rogue/Mage will always be OP and Warlock will always dominate end of season or expansion (You can also add DH to that mix).
