The function of the rover isn't to drive around and map things. Its function to serve as a platform for a suite of scientific instruments to gather data. That

The function of the rover isn't to drive around and map things. Its function to serve as a platform for a suite of scientific instruments to gather data. That suite of scientific instruments will be different for the next rover, adjusted based on what we now currently know (and didn't know the last time they chose instruments). So, yes, its "another" rover. But its what that rover is carrying that is different and interesting. Having said that, I'm all for being a lot more ambitious, and sending people to Mars instead. But that's a different discussion.