I mean, If I walk from Riften to Marcarth, I encounter at least two dozen wolves. Now while this isn't a problem for my character, I can't help but think it would be for a carriage with nothing guarding it.
Also, I think it would help make the world feel bigger if the carriage was too expensive to be viable for a period of time during the start of the game. Perhaps 200 septims for a short trip and 500 for a longer one?
In a game design sense this would force exploration and might avoid some of the complaints people have about the length of certain quest lines?
Please don't take this as a complaint, more so an observation.