I do think the volume of trading is down. In capped leagues trading is tougher because trying to have the two teams caps balance can be tough. In live draft leagues, trading is much easier, although the manager can get the guys he wants in the live draft as the draft plays out rather than hope to get the guys he wants in a capped draft.
Sometimes I see a trade made between some teams and see a perfectly balanced trade, and others I see a Ruth traded for Delahanty and Rollie Fingers and cringe. I've seen tempers flare at unbalanced trades that make an average team a contender esp. when the new contending team shows no remorse or conscience.