The problem is that the data is encrypted, and too many bad password attempts will delete the encryption keys - making the data permanently inaccessible. The FBI wants Apple to create a tool that will bypass that security. I’m not even sure such a tool can be created, but it is an accepted fact that it does not now exist. So the question becomes, do we want to set the precedent that the government can force you to create something new, even against your will? I am not talking about forcing you to turn over something you already have - this would be creating something completely new.
It is very likely the government can remove the flash memory chip in the phone and save the contents. After doing so they can wipe them out over and over again trying to break the code without the risk of losing the original encrypted data.