They have an actual purpose!
It’s true. You can now trade in PlayStation trophies for Sony Rewards points. Which, presumably, means you can get games for playing games. Very, very slowly.
All you need to do is sign into your PSN account, join Sony Rewards, and start earning trophies. So, yeah, sadly trophies you’ve already earned prior to linking your account aren’t eligible for this treatment. But it’s still a nice way to get some of those bonus items, right?
Each reward point is worth about a penny; which means that it’ll take a few more lower level trophies to get what you could for a small number of high level trophies. The conversion is available here. So getting $10 of PSN credit will take 10 platinum trophies, or 100 gold trophies, or 1000 silver trophies. So, get your PlayStation on and earn that new game.