What you think of as important may change over time, as well - with the solution as written, you’d need to decide what the “subject” is at compress time, but what if you later realise that’s the last ever photo of grandma, or the AI decides that you were wearing different shoes than you actually were. Worst case, you need to rely on some detail in a photo later, like to absolve you of a crime.
The good parts of Reddit came from Aaron Swartz. Everything since then has been these guys trying to squeeze as much money out as possible (remember Reddit Coins?).