The first beta weekend I played I didn't know that you could cast while moving. So I kept stopping to cast spells and was getting clobbered. Then I saw another Elemenalist running by casting as she went and I was like Whaa...? And that was it, I was off!
I think some people take to this game like a fish to water and others, well, maybe they are too entrenched in old habits or just don't care for this kind of playstyle.
Personally, I love it