If running out of gold isn't a concern, then it's not really a currency, just an extra trip to the shopkeeper every once in a while. They could just give everyone unlimited consumables and remove gold from the game, and it wouldn't affect much of anything. I'm not opposed to have gold exist, but if it does, then it should…
There are unlimited respecs right now. Why is it so much more palatable to you that people have to pay with Zen rather than some other currency? Even with unlimited respecs, your choices still matter. Every power or feat that you take is a point that you can't put elsewhere-- everything comes at the expense of something…
I think it's nice that you don't need to do every zone to hit 60. It means that if you level another character, there's stuff that'll be new, instead of a retread.