Why are some fights 10 rounds?

[MaTTuP]

This probably sounds like a dumb question but it just seems like too short for a fight, especially since they used to go 15. How do they decide when to make a fight a 10 rounder? For instance Gatti vs Ward I-III. Is it because they knew that neither of these guys cared much for defense and would dish out & take massive amounts of punishment without getting ko'd?

[Silencers]

10 rounds are for non-title fights, although if there are big enough names in a non-title fight, it somehow becomes a 12 round fight.

[Miburo]

Because not all fights are championship bouts. 10 rounders have always been well-established, usually for bouts of slightly less importance. With the elimination of 15 round bouts 12 became the championship/top fighter standard. There is some inconsistency when titles aren't on the line.