(Im responding the the original post btw
)
Well, once water becomes more needed then it is, i would like to see it so that you can import / trade for water.
When toady gets more into things, you can start up a "Settlement" in a desert, mainly for the purpose of mining the raw resources.
Maybe it being some kind of minor side quest / mission thing, where you can goto a desert and mine as much as you can and survive as long as you can from trading back to your mountain home as much ore / metal / gems / resources as you can.
The longer you survive, the more you export home, the more your dwarf race grows and becomes more powerful.
Once wars are established, going to the desert as a mission to obtain resources, would make your race more powerful and able to take over goblin settlements / city's and such, or just build bigger armys to defend your city's / settlements.
The deserts would be mini settlements, only being able to support 20 - 30 people, with its own government structure, never having a economy.
This would of course only be for "Deserts" sand deserts or barren deserts, or even tundra. Any place where you wouldn't normally have a thriving settlement with a full economy.
This is what would like to see toady do in the future