RE: Had to post this bit of personal UAV history
There were two primary reasons that compliment each other. On a purely practical note, as the UAV was designed for shipboard operation with a vertical net as the capture system for recovery, I reasoned that with the appropriate spacing, the odds were good that it would punch the nose and foreword surfaces through a net square and hook in, so the springbuck wouldn't toss it back on the deck.
The other seemed to play well with the intended flight profile. Its mission was pure search, and the planned, somewhat docile pattern had very little vertical component. To increase the duration, lower the main wing loading, and reduce long-moment elevator deflection, this seemed a good solution, and it conveniently worked with the recovery requirement. There was also a slight advantage to how it affected the flow over the main wing strakes at higher angles of attack during recovery.
That was my thinking at the time
Cheers
Kevin