whats so good with gambits losing a piece for free

Most gambits dont gambit a piece but usually a pawn or 2 is more common. And such "gifts" are never for "free" they usually grant the gambiteer a lead in development, which in turn can become a dangerous attack. Gambits teach a player about initiative as the gambiteer almost always has the initiative in return for his "investment" .

I think its important also to distinguish between a sacrifice and an opening gambit. One is a tactic while the other is a strategy.

Sacrifices are not always tactics!  Some can be positional.

Kings Gambit for instance opens up a line of attack.  Pawns are clumsy little creatures that get in the way in the beginning.  By sacrificing the early kingside pawn you open a line for your rook after castling.  The pawn also has no support and can be taken when the time is right for free.

You people are horrible!

Gambits are so great because they're a ton of fun!!!

C'mon.. isn't that was chess is all about? (well, at least until the 2700's!)