I assume because it's still a great position for a base (wide stretch of easily defendable flat land) and the infrastructure is already there. Plus, anyone cap

I assume because it's still a great position for a base (wide stretch of easily defendable flat land) and the infrastructure is already there. Plus, anyone capable of seriously surveilling such a well-positioned base will most likely also be aware of any other "secret" base that's usable for launching stealth aircraft; the space requirements alone make those hard to hide.