If you look at the map of Tamriel, you'll find no significant waterbody in Skyrim besides the sea shore up north. So row boats wouldn't be present in the game at all.
I think that's just an oversight on Bethesda's part. If you look at a map of Tamriel, the only real rivers come off of the inlet that leads to Cyrodiil from the ocean. Frankly, that's just not realistic geography.
There's bound to be streams, rivers, and lakes, and even without them, there is that huge coastline, with several important cities on it, which is enough to justify boat travel.