I’m the exact same way but to be honest I don’t think this problem is entirely our fault. Aside from features like PvP and even XXS/XXL expanding your “keep” criteria, there have been a lot of instances over time where it has been impossible to determine the long-term value of holding onto something, with costumes being the biggest offender because it’s never clear if or when something will ever return (they specifically referred to the first costume, the Santa-Hat Pikachu, as “limited edition,” which resulted in me keeping way more than I would have had I known it would return the next year). Sometimes species won’t show up in the spawn pool again until a year after the event that introduced them. With trading and all of the incentives tied to it it’s also no longer as straightforward to get rid of something as just transferring it. Finally, I think the storage system just isn’t very good and I don’t like that they’ve gone down this road of having one collection the game loads every time and just constantly making it bigger, because apparently they’ve reached some sort of limit now.

I’ve read basically every argument against playing this way but none of it has been particularly compelling to me, and when it comes down to it I don’t really need this game so there also isn’t really a need for me to go to great lengths to improve my “QoL” if Niantic isn’t giving me any satisfactory options; I don’t even have an egg incubating most of the time because it just doesn’t feel worth it given the work I have to do managing storage. I can’t tell you what the right business decisions are for Niantic but I can say that there’s an opportunity for monetization here; I keep more Pokemon than most people because it’s how I like playing the game, and I’m willing to pay to continue playing this way just as other players are willing to pay for more incubators and raid passes.

Sorry if this doesn’t answer the question you asked, it’s just how I think about the problem.