With the addition of the forge system, heating gear has become excessively slower especially with the radiant drought. We are only allowed to excel up a single level per floor in the arcade, after which case we have to forge the item. Heat amps were originally meant to boost the heat of a gear so much that you can easily gain a level in a single floor, or even multiple levels in high heat-output floors, but the forge has rendered that impossible.
So I ask: What is the purpose of heat amps now?
Nah. Heat amplifiers are for really really impatient people.
Skyguarder, it wasn't me. Setting aside that possible appetite effect for a moment...
For free-to-play players, there has never been a purpose to heat amplifiers. Heat has never been the bottleneck in the crafting process. Before release 2013-07-30, saving up crowns to buy energy to upgrade always took longer than acquiring the heat needed to upgrade.
For most pay-to-play players, I agree that heat amplifiers are much less useful than they used to be. But, for high-spending pay-to-play players, who actually spend real money to buy 5-star fire crystals, I guess that heat amplifiers could still be useful.
It just seems like heat amps (among other things) have been left behind in the development process. It has become obsolete, and unless they change the heating system again - or the item itself - I don't see it ever being useful again. Would be nice if they exchanged heat amps for items that increase fire crystal drop rates, or something similar.
According to Qwote, Bopp or Zeddy (I think one of them mentioned this), heat amplifiers can make sprite appetite go up and level up faster.