The game has a "design flaw", in that you can max out your items very easily, by taking them to 5 stars and heat level 10. Once you're maxxed out, there is nowhere to go. For example, all of my heat in 2013 has been wasted, because I haven't had anything to heat (except for my sprite). The game would be better if you could always make your items slightly better, over long periods of time. Perhaps 5-star items could have unlimited heat levels, with damage stats that keep going up (by less and less, perhaps approaching an asymptote). But actually, there are two ways that you can keep improving your equipment in the long term.

The first way is unique variants. The high-powered ones are so rare/costly that most players will never approach the perfect Blitz Needle, for example. But they can keep saving money, rolling Punch, and crafting, in the hopes of one day getting perfect UVs.

The second way is this new forge system. You can stop heating your 5-star items at heat level 5. But eventually, if you keep playing, you will acquire so many fire crystals that you might as well finish heating your items. So I agree that 5-star-heat-level-10 is now something like an endgame goal for highly experienced players with nothing else to do. It's not just a status symbol, because it has some slight practical effect. But it's close to a status symbol.