We can't assess anything yet, for a short time Destruction was playable on Alpha without artifact you could run around and frikkin bury things with a bunch of instant casts.
I'm not even sure what you base the mobility issue on, you realize Shadowburn is now usable on targets with any HP% and you can cast 10 of those in the row if you spec into it and that our DPS cd now is a guardian and thus active regardless of us standing still or not?
Being able to bury things with instants is a bit discouraging?