I basically agree with everything you've said here. I particularly like the clarification you made regarding efficiency, whimsy, and fun. In this regard, my primary grievance with GW1 was that too many players idolized the highest efficiency as the only way to play. It wasn't even just that whimsy was punished but that being unfamiliar with net-bars, not having this or that specific elite, or simply wanting to make any deviation for the sake of preference was ridiculed. (As an aside, I really disliked how badly some players ridiculed others who fell into the "trap" created by GW1's false choices. Players who made "best possible" bars out of suboptimal skills deserved praise IMO.)
Consequently, I am cautious of any argument that praises efficiency as a virtue. (I realize that efficiency IS a virtue.) It's also why I am okay with the "dumbing down" of GW2. It has capped the effectiveness of efficiency sufficiently that some whimsy (read: variety) is permitted. I don't think that they've achieved the ideal solution - only that I prefer a game that permits some whimsy to one where the content combined with the community permit only high efficiency.
Regarding the present changes to the trait system, I don't think it significantly affects the efficiency/whimsy balance, which is probably the fulcrum of many other people's complaints about GW2 in general. I would enthusiastically welcome changes that would genuinely reward and encourage a variety of builds. I'm much less enthusiastic about changes that increase the apparent complexity of the game while, in reality, just introducing a broader diversity of false choices. That would only confuse some players and frustrate others by showcasing the increasingly many ways in which the game could be played suboptimally.