I hate when people say "you can't roleplay in 4E". There are no rules for role-playing, because there doesn't need to be rules for role-playing. My 10 yr old son was role-playing while playing the Castle Ravenloft boardgame. You can roleplay while playing Monopoly for crying out loud, if you wanted to.
Do skills reduce the need to roleplay as much? Yea, I can see that point. But, IMO, skills should be used to complement actual roleplaying. I personally sure don't have an 18 CHA, WIS, INT, DEX, or any other ability, so having a skill system helps show what my character can do that I really can't. It's not fair to say "If you want to swindle someone, lie to them, or try to get past a guard using your wits, then you have to roleplay it, there is no Bluff or Diplomacy skills." without telling the guy with an 18 DEX that he personally has to really run along a 1-inch wide ledge if his character does or that a player has to show how his 18 STR fighter busts down a wall.
Skills definitely have a purpose, but it doesn't take out the need or the existance of actual roleplaying IF the players want to roleplay. Also, some players might not feel as comfortable as others roleplaying or might not be as good at it as others, so they shouldn't be penalized for their lack of RP skills either.