They're not worth researching anymore after Relic didn't compensate for the flame crit change on them. Maybe on maps like semois with tons of buildings and cover you might still get them but on more open maps they're just a huge waste.
Wasn't flamecrit chance applied just for flamers?
They specifically named flamers and infantry flamers in the notes, nothing really about stuff like molos or incendiary arty(which would be an huge overnerf).
Other then that, the higher rank you play at, the lower molos effectiveness is as they are 100% dependent on opponents lack of awareness with shortest range and longest throw animation.
Though I'm pretty sure alex will come here, preaching how molos are best nades in the game, will boast how he torches whole armies with them and will not provide a single example of the ones inside of his head.