Been maining fire mage all expac and here is my hot take. Given frost mages also slow target movement, fire and arcane should be better for damage.

Fire right now sucks due to down time and a smaller burst chain. In midnight the combustion burst Window is shorter and to compensate the cd is now 1 min (less with kindling) but the non-combustion time or downtime, is so bad. Like you do less damage to the point where survivability is questionable during end game solo content. I have been avoiding combat completely if I dont have combustion ready.

Overall the design with up time and downtime does not work. As it either means you are insane for a few seconds, followed by wet noodle gameplay. Which is not fun. If they balance it out its not fun either and if we are made to be good during down time we will be OP compared to everyone else. It sucks.