I've read in a lot of places that having two objects colliding with each other where the mass of one is over 100 times greater than that of the other will cause issues with the physics of the collision. However when I tested it myself I found no real issue with what I was trying to do.
Essentially, I'm hoping that someone can elaborate on why it is a bad thing to have the masses so wildly different between two colliding objects, as currently I haven't seen any reasoning behind why not to do it, just lots of high rep people saying don't do it.
There is not one with the information you have given.
Have you ever collided with a bug while driving? Was there some catastrophe, when it happened?
If we are placing value judgements on physical phenomenon, then it would probably be "bad" from the bug's point of view.