Well mainly because most bugs aren’t doing anything harmful. Those removal services are to prevent damage or harm that can occur. A spider hanging out in the rafters is not hurting anyone. If the visual of a spider and a web is a problem then relocating them seems to be most reasonable.
If you have a line of ants show up, figure out where they are coming from and plug it, and then trap the ants and put them out side.
The question shouldnt be why let them live, in my opinion. It should be why should we kill that specific bug or five bugs or ten. Even a lot of those businesses that remove bugs and animals will do so non-lethally if possible. They can move whole nests in some cases
I understand you have a fear but it can’t be healthy to alleviate that fear by killing the cause of it whether its justified or not.
Yeah the ants are annoying, they seem to come through my house every so many years during summer. You see one and then realize theres a whole bunch of them all over. They can be tricky to deal with.
I won’t defend mosquito’s though, they are the worst.