I have a hunch that this might form part of our missile defense program; the US has talked before about actually shooting down ballistic missiles in space.
Maybe...
The other detriment to having pilots is the artificial performace limits that would need to be set in order to avoid hazardous G-forces.
Ironically, the first story I ever sold to ANALOG science fiction magazine, was about a manned ICBM interceptor. I couln't interest the Air Force in the idea, so I did the next best thing. The story, PUSHBUTTON WAR, appeared in the August 1960 issue.