If the ballista didn't require ammunition and essentially manual activation, I'd understand the frustration. It's far more important to make it effective against targets, even if it includes players. Right now it's utterly useless overall but shouldn't remain like that if the public test branch changes are working.

And finally, ballista use isn't the only choice you get to make in this game that has drawbacks. Almost everything you do in Valheim creates drawbacks in some sense or reduces your options. What do you carry in your inventory? Which weapon skills will you focus on training? What food are you eating? Which Forsaken power are you going to take? Are you going to prime this ballista (or the other one pointing other way) or fight the event off on your own?