I think that, traditionally, the 2-3 zone was played to keep teams from exploiting the inside game by playing three players across the block. This makes it much easier to form the rebounding triangle ( I found a short explanation here
(http://www.coachesclipboard.net/ZoneRebounding.html)). In a 3-2 this is not as easy to do. In man to man the rebounding is up to the individual matchup.
Once I scored a basket that still makes me laugh.