Does it though? I suppose it heavily depends on your definition of "fighter", but cranked-kite and flying wing designs have been the go-to for subsonic stealth jets and UCAVs. Under a "something that is intended to kill other planes" definition a subsonic stealth air-to-air platform with good sensors might qualify as a fighter, but many people seem to think "fast, hypermaneuverable" are requirements too. Confusing the goal with the method, IMO.
Another major design constraint difference between "unmanned fighter" and "cruise missile" would be the deployment and reusability goals. Cruise missiles tend to need to fit in launch tubes or under wings, while presumably an unmanned fighter would not be so constrained (and thus be able to use larger wings). And while cruise missiles are very single use, the sensors on an unmanned fighter may make it too expensive to discard that way.
Another major design constraint difference between "unmanned fighter" and "cruise missile" would be the deployment and reusability goals. Cruise missiles tend to need to fit in launch tubes or under wings, while presumably an unmanned fighter would not be so constrained (and thus be able to use larger wings). And while cruise missiles are very single use, the sensors on an unmanned fighter may make it too expensive to discard that way.