It is kind of fascinating how different our approaches can be to the same (or probably more accurately, similar) hobby. I approach writing game rules in the same way that I approach work projects. What do we need to do, what are the limiting parameters, how can we do it? My approach to rules is to create few simple mechanics, in which a wealth of details can be used, and endless choices can be permitted and accommodated. A very dispassionate approach to rules really, and I think somewhat the opposite of you. A curious contrast as I completely share many of your thoughts (that you have shared in other posts) about the passion for the game, the art of the game, etc.
Long ago I started with board games, but quickly moved away from them and almost exclusively toward miniatures. Most of my board games are just “fact witnesses”, bits of research data. I almost never consider board game rules, when creating miniatures. Obviously, the experience and knowledge gained from board games is there, but the conscious focus is on what real world (or fictional) process needs to be modeled, and how can it efficiently be modeled. I probably re-invent the wheel a lot, but as long as I enjoy it, I guess maybe it doesn’t matter.