What 'skill' was there under the old system? Checking server statistics every month to see whether Blissey has fallen enough to put a special sweeper on your team? If anything this will make for better mindgames. Magnezone knows that Skarmory knows he is in the wings. Does the Skarmory player switch out immediately and waste a valuable turn? Does the Magnezone player take it since Skarmory didn't switch out he is running shed shell? Does he whirlwind right away and give away he doesn't have shed shell? Or is he bluffing?
I dunno, my favorite part of every battle is when both sides know the remaining roster and have to make crucial decisions, not so much 'gotcha' switchins. Now, items and movesets are still hidden, and honestly I feel movepools are better for surprise tactics. Ditto notwithstanding.