I mostly agree that excavator is the only actual useful thing in pve, but then again, if the OP part about stryders can be disabled, then why disable them? even if what's remaining is mostly useless or inefficient?
I mean, there are many creatures that are absolutely useless but they are not disabled.
also, it doesn't always have to be about efficiency, could be just for fun, tame a stryder with cannon and go kill wild creatures or something, my point is, it's a part of the game anyway, and if it wouldn't hurt the server to have them, then why not?