Firebolt spam is already pretty powerful bordering on op in the first place, adding a surface AND a burning effect on it is just garbage design.
It also came at the price of nerfing the base damage by 40% (given it went from 1d10 damage to 1d6 damage plus DOT).
If you ask me, firebolts are arguably more powerful now that they fit the ruleset, at least in terms of burst damage (which is often what really matters).
Still, you won't hear me complain about having less DOTs and surfaces in the game, that's for sure.
It's just that I didn't really give a damn about it, compared to other more fundamental flaws.