Say I have a small problem which can be solved easily by myself. Yet I don't do it because of some unimportant thing, and this involves many people and generates many debates, making everyone fed up. Is there an idiom or common phrase for this?
You seem to want an idiom where the effect is felt by others, rather than just by you, so one of the phrases we use to stress the value of early action might be a good choice.
A stitch in time saves nine
comes to mind. The idea is that when something starts to go wrong immediate action is better than delay.