Have you tried Sid Meier's Pirates!
You can ignore the basic plot and just be a merchant and gauge your success on the money you make.
You can experience defending yourself against pirates. Of course, this is only in sailing ships.
The problem, I would think is that it would be boring after a while. Just like real life merchants. A repeating set of ports, trying to keep costs down and profits high.
Might be interesting as an economic simulator, but as a game, I don't see how that could be fun after a while.
I guess there is a reason why most of the games out there involve combat in one way or another.
