Depends on the DM. My first 4E DM assumed that players had to explain what they were doing, not just rolling dice. Even experienced role-players had a hard time coming up with arguments for our 4th and 5th checks. Less social players had a hard time coming up with one.That's quite the opposite of my experience - giving the "less social" player a mechanical element to work with pulled them in far more than asking them to improvise. Probably depends on the player.
I did play in a different group that just rolled out skill challenges. For a Watcher this might have been good, but as a Roleplayer, it was totally disconnected with anything going on in the game. We just rolled dice and the DM told us if we passed or failed, and the consequences. Innovation and RP was strictly discouraged, especially when it broke the skill challenge (such as when I figured out a riddle long before we succeeded in the skill challenge to solve it).