The FBI's request isn't too bad really. It's not like they are requesting Apple to build a new mass surveillance tool or anything similarly far-reaching. This is limited to the domain of digital forensics, and how best to extract data in a criminal investigation, against firmware that is hostile to cracking. Given that, by design, the phone has been locked down to only accept Apple-signed firmware, then Apple is really the most feasible choice to assist in bypassing this.