In addition to other comments above - I think a sweep helps the C's confidence. Coming into the series, this was supposed to be THE matchup, with the C's "trying to dodge" Miami and get Milwaukee, b/c they feared the Heat. And there was a question if the team could turn on the switch for the playoffs. A sweep will do the psyche good.
Additionally time for the coaching staff to game plan and scout, and follow up with practices will be critical. Also this team can use rest whenever they can get it. Rivers is correctly playing Rajon Rondo (43), Ray Allen (37), and Paul Pierce (43) a lot of minutes. (Tony Allen only played 14 and Finley 4.) With the spacing in the first round this is easier, best to rest now when you can.