Sometimes I have to bash several times to interrupt a caster. Sometimes I have to taunt several times to draw aggro in trials and dungeons. Lately, there has been a lot of button spamming required to even fire off skills.

Did you test this in a lag-free environment, like against random mobs in some low population PvE zone? If it doesn't work there, the problem might be unique to bashing or even to this particular set. If not, I'd say it's just another sign of general lag and desync. The set works fine for me, but it seems like everyone is having their own particular set of bugs in this game...