Well, there's two ways to look at why to bother having even approximate numbers in my view.
#1 is that we already have approximate numbers for speeds, they're just kind of confusing and maybe more harm than good. Things will always move at the speed of plot, but I at least have often found it handy to be able to at least do a back of the envelope check of whether something makes sense or if it's at least sorta consistent with what other people are writing. Say, having Earth to Mars be a fairly trivial trip that most vehicles can do in an hour or two, or having Earth to Mars be something that takes the better part of a day and most people do in larger vehicles than cars... either versions are okay, but it feels weird if some people are assuming one and others are assuming the other in what's supposed to be the same universe.
#2 is that I'm an engineer.
Or put a different way, I and my avatar are both engineers, and both of us are into going fast, racing, and so on. And, not that I'm a hugely prolific writer or anything (obviously) but I've actually ended up feeling hamstrung for a long time because I kind of can't really get into this stuff that's a big part of my character in stories, or at least not in any way that's close to how I think. If I can't tell if things are even going to be accelerating slowly enough for humans to react to, it just feels like I can't really write *anything* about that whole category of stuff without stepping on toes by defining precedent, or being wrong.
It may be an edge case, but it's my edge case.
#1 is that we already have approximate numbers for speeds, they're just kind of confusing and maybe more harm than good. Things will always move at the speed of plot, but I at least have often found it handy to be able to at least do a back of the envelope check of whether something makes sense or if it's at least sorta consistent with what other people are writing. Say, having Earth to Mars be a fairly trivial trip that most vehicles can do in an hour or two, or having Earth to Mars be something that takes the better part of a day and most people do in larger vehicles than cars... either versions are okay, but it feels weird if some people are assuming one and others are assuming the other in what's supposed to be the same universe.
#2 is that I'm an engineer.
Or put a different way, I and my avatar are both engineers, and both of us are into going fast, racing, and so on. And, not that I'm a hugely prolific writer or anything (obviously) but I've actually ended up feeling hamstrung for a long time because I kind of can't really get into this stuff that's a big part of my character in stories, or at least not in any way that's close to how I think. If I can't tell if things are even going to be accelerating slowly enough for humans to react to, it just feels like I can't really write *anything* about that whole category of stuff without stepping on toes by defining precedent, or being wrong.It may be an edge case, but it's my edge case.