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I didn't mind losing 3D because at least it felt like we were moving (mostly) forward.
My biggest problem with the 3d client was the same problem I have with the EC... 2d Legacy graphics simply DO NOT zoom well. In 3d, the models were crisp, clear and smooth, but the world graphics got distorted. In KR, only at the highest zoom levels did you start to see pixellation, EC is the lesser of both clients in this regard... distorted world graphics and pixellated model graphics.
The problem I had with losing the 3d client was the roughly 2 weeks or so for those who didn't get into closed beta between the time that KR was in closed beta and they shut down the 3d client and when they finally let everyone into the KR open beta. After that, life was good.
I was even fine with going from KR to the EC when they let us modders in the initial closed focus group/beta, but when they downgraded the graphics, tore out popular portions of the UI, and then put all of the focus on the expansion (at the cost of the client and really doing very little of what we were initially focus grouping about), that bothered me.