Every interface convention was novel at some point. Breaking them doesn't necessarily make a UI bad, just as following them doesn't make it good. It depends on your skill as well as your audience, their expectations, and how experienced they are with the current interface patterns.

But certainly the vast majority of products should not create new or novel interface patterns just as they shouldn't "roll their own" cryptography -- it is almost always unnecessary and unless it is your primary focus it is very likely that what you come up with will be significantly worse than the status quo.