Nobody is trying to kill people at weddings. In fact, most of those scenarios would not have happened if there was intelligence it *was* a wedding. The only intel that is usually received is that some high value target was going to be there.
Mistakes are made and perhaps too often. And that *is* a reason to reconsider the drone program. However, that's because it may become counterproductive to defeating the terrorists, not because it is "cowardly".
A terrorist might actually be what used to be called "physically brave" in that they are willing to die or take harm for their cause without flinching. That's important, but they tend to be what is called "moral cowards", because their physical bravery is put to the use of evil.
You can't call a drone pilot a physical coward in the same way. The drone is their weapon. Would you send lightly armored archers into a press of armored cavalry? Hell no. They'd get smashed and do no good. Their weapons are arrows and being light and maneuverable. They're not going to run at and hit knights over the head with their wooden bows or something. They'd get slaughtered.