Why would it be simpler? I'd have thought it would be harder as they'll have to simulate something we don't have good empirical data for. Taking Titan as an example, we know that it has methane-ethane clouds and that it has definite weather including wind and rain (which would presumably behave differently to ours because of differences in chemical makeup, gravity, etc.) and this in turn leads to features like rivers, lakes, seas, dunes, etc. What we don't have a good handle on are the processes that lead to these features. Frontier will have to take what we do know (e.g. from observation of Titan) and extrapolate that into a generic model, including the modelling of tidal forces. It's going to be a lot of work.You are right about the weather simulation, but even that should be much simpler on planets without any significant water supplies.