Could it be bad if i never get a crown replaced after my old crown falls?

Yes: Unless you have a well fitting crown on an intact tooth free of decay, you will most likely have problems which may lead to losing that tooth altogether. Get the tooth fixed and the crown replaced. If there is a problem with that, discuss it with your dentist and try to work something out. If not, you will be sorry in the end.

Yes: If your old crown failed you are at risk for more decay pulpal infection (if root canal was never done on that tooth) and the possibility of eventually losing the tooth.

Fails?: If the tooth needed a crown before, it still needs a crown. So if you had one fail, it still needs something over it until a crown can no longer be done.