And it isn't just in hard scifi that granularity matters to me. I love Savage Worlds, but I have some problems with the system in long campaigns or back-to-back campaigns. Savage Worlds does not have a very high level of detail in its skills, this is great, it is what makes it so fast and easy, but it can make everything start to feel the same after a while. I have found that two Savage Worlds campaigns in a row can feel very much the same, even if they have very different themes, because of the simple mechanics. It is also hard to keep things mechanically fresh over long campaigns. I do not think this is an actual flaw in the system. The game was designed to be "Fast, Furious Fun" and mechanical granularity is going to be one of the trade-offs for that. GURPS, on the other hand, takes a while to get up and running, but offers many ways to make things feel very different due to its detailed, modular nature.
I like long campaigns. I like spending a lot of time working on the game world, and campaign specific rules before the first session. I want to distinguish this from something that requires lots of prep time every week before play, like Pathfinder. GURPS requires a lot of work setting up the campaign, but very little on a weekly basis. GURPS gives me the ability to make a very realistic world, and to fine tune the game systems to get the feel I want.