On the one hand, it's not a huge amount, on the other hand, it quickly adds up to five figures if you constantly spend a few thousand more here and there.
Exactly, that's it. If it was just one part that you upgrade, but there are so many opportunities... You just have to weigh what the priorities are. If you didn't have a lift-and-slide door before and weren't bothered by a threshold, it might just be a nice-to-have and you can manage just fine without it, same with other things. You'd rather upgrade the things that would otherwise bother or annoy you or that you really want to have.
I had written that our neighbors threw out their sliding door after a few years and replaced it with a lift-and-slide door. They had exactly that tilt-and-slide thing. I never dared to touch it either; you had to pull it toward you with some force first, I was always afraid because I might break something, this opening principle was totally unfamiliar to me. The children actually couldn't operate that part themselves either (which isn't necessarily a bad thing, depending on the child...), whereas the lift-and-slide door is no problem to open. Our kids at kindergarten age have already managed that.