What do you mean by "no reason" though?
Absence of a good excuse.
I don't think that's morally questionable. Does anyone think it is?
I think it's objectionable. Dunno if I'd say morally, since that has a lot of important connotation, but it does not please me. Spiders especially. I've punched someone for killing a spider when I asked them not to. I am aware of the hypocrisy when I inflict harm on a thinking, feeling being for harming a thing of little-to-no sentience. But that's what is in my fucked up little heart.
I think what I object to is the absence of consideration. I feel bad when I have to exterminate an invasion of ants in the kitchen, for example. I cannot sufficiently explain why I do. It just seems unfortunate to me on some level that even such small insignificant things must be destroyed, and it manifests as upset. I wonder why some people do not feel bad when they do this. Some people lack that, and that unsettles me somewhat. Even when something like that is necessary, this does not mean there cannot be that consideration.