What actually is rather limiting also is the available map set. Now before anybody goes there building a historical terrain for use in these events is much, much time consuming than building a non-historical terrain for the MA. Basically the designer is doing research to get the right elevations of the terrain, trying to match coastlines, roads, base positions (in many cases) and also then creating the textures for the terrain and Special Objects.
It is a lot of work and every time a new TE or OE comes out everything needs to be tested to make sure old designs are still working with new designs and that old ways of doing things still work with new software. This is why map production for events is slower than the MA.
So we have the maps limiting us to what areas we can do battle in and then we have plane sets as you guys point out.
As for the past 5 FSOs we have done 1 Pacific, 2 ETO, and 2 MTO. Yes, another Pacific one is do and is coming up (another Admin is planning a Pacific event) and started planning his before I did mine. I am before him in rotation but I didn't want to run an event on the same terrain he is using almost back to back.
That left me with the option of an event using the Tunisia terrain, doing Husky or the Siege of Malta (southern Med events in contrast to the later Italian event previously run), or something in Hungary. I will admit to a bias here that the Hungary Map doesn't perk my interest so I didn't go with that. I have already run a Tunisia event back in 2008 so I decided to go with a Southern Med event and decided to go with the Invasion of Sicily for a couple of reasons.
1) I could incorporate British Fleet Carriers in the event and have the FM2 stand in for the Martlet. So I thought that would be a nice change of pace to have British CV operations (Seafires and FM2s).
2) With people being able to man the guns of DDs I thought it would be interesting to do an amphibious invasion battle. Have a couple squads man DDs and LVTs and try to take a base while being resisted by shore batteries and GVs.
So of the available map options open to me Sicily I thought provided the terrain with the most possibilities for interesting twists. This is why I went with it.