Absolutely not. The trading is the whole point. You talk to each other, you negotiate, it's interactive. Sure it means the same person always wins, but it's the interaction that keeps it alive.
It's a difficult issue because I think the trading is also the core of what makes the game interesting; it's hard to force players to cooperate with their competitors while avoiding the kingmaker issue.
I played another game fairly recently where people could negotiate trades for resources. Also a mistake in game design. I want to say it was Moonrakers?
You can make a deal with another losing player to maximize your chances of winning. On the next dice roll, seven or above you trade all your cards for one, and vice versa. However, all contracts are nonbinding in Catan so it never works out
