Frostfire bolt procs feel more like its an interuption of your rotation rather than helping your with it on Fire mage, because it pretty much just destroys your Hotstreak and its pretty much just a dps loss and wasted proc to use when you got your other hotstreak builders up.
Making it a 100% crit on instant cast procs would help fire mages alot with smothing up the rotation and making it a viable option to use over sunfury for Fire mages.
It actually is already supposed to work that way - Frostfire Empowerment makes Frostfire Bolt guaranteed to crit and deal 50% increased damage according to buff tooltip. It is just bugged and neither triggers guaranteed crit nor increases damage currently.
Its buff tooltip mentions it (the buff on character). And it did provide guaranteed crit in beta till they changed Frostfire Bolt to the Frostbolt like mechanic (effect on hit instead of effect on cast) and that broke many previous interactions including some effects of Frostfire Empowerment.
Small update for people who don’t know yet - Frostfire Empowerment was stealth fixed and now properly makes affected Frostfire Bolt guaranteed to crit. No tooltip update in hero tree though.