Obama: "I'm ready to negotiate with you, Iran." Iran: "Fuck you."

[classicman]

It was also reported that they fly similar to a radio controlled airplane. The US knew of this weakness and intentionally did not put anything in them that would be compromised "when" one went down. According to the US.
Also - from PH's link:

this is a fairly simple airplane. I doubt if there's anything radical in terms of reconnaissance equipment on board. There aren't that many examples of a huge intelligence haul of that kind coming from one particular aircraft.

And another link