As it stands, players average a whopping 6-12 radiant fire crystals after FSC/after an arena run, and the only depth at which to harvest crystals is D28. This means that not only does it take time to get to the depth at which radiants are dropped, not many drop period.
Buying from the supply depot, at 700 CE/50 crystals, will cost ~6300 CE per 5* item to heat to full completion (assuming all 100% routes are taken). This is an absurdly high cost, and very few players will take the time and effort to devote this much energy into completing one item.
There are 3 good ways to fix this:
1) Revert the drop rate of Radiants/increase the drop rate. It was fine before, don't fix what isn't broken?
2) Make radiants cheaper in the supply depot. Significantly cheaper.
3) Make recipes for radiant fire crystals to be crafted from lower tier crystals.
Radiants are a horrible game mechanic as they stand, and will dissuade many players from playing even before they start. Please fix, OOO.
Actually, noobs would have to get up to at least 3 star before they start caring about the system. Then they will complain, and get their thread trashed in 3 seconds because all people care about now is that new boss.