Also, IIRC, the Fire Phone was heavily influenced by the personal involvement of Jeff Bezos himself.
AT&T could only push that pile of crap so far, they really did have their sales teams push it hard though. Very hard to convince a customer to get a Fire phone rather than a Galaxy S4, or even an S3.
When the Fire phone was on Fire sale, it was a pretty good value for users though. The launcher was weird, but you could smuggle Google Play store on it, and it had a good processor.