[RomP]

It's similar to saying that having expendable bullets and grenades is OK until you use the last one while still on patrol. Solution: preparing for it by taking more. Knowing that they're designed to fail/be repaired easily changes the approach. The argument I'm trying to make is that it would be cheaper/lighter/more_versatile to get many expandable droids than to get one robust and universal.

Also, highly-adapted droid != highly-adaptable droid. There is no need for an amphibious droid in Afghanistan, just like one doesn't use the same apparel in all climate zones. As long as interface/principles are the same (like a PC), various versions of it can be used in (almost) any environment without extensive re-training.