Why do/did you go for runtime reflection for all that? I thought you would use it for external scripting or mods or things like that, but not for eg serialization. I guess I am missing something.

Everyone misses compile time reflection because it solves many use cases easily (like serialization) without having to go for a complex solution or incur in performance penalties of runtime reflection. In contrast, I doubt many people care about general runtime reflection which I’d expect to be a mess in C++ and most likely not as fast as people wanted.