I do have to agree with you on this. From my own experience its common for beginners and those of low rank to be really concerned with belts. At higher levels you're not as concerned. Some people will get to brown belt or black belt and then they will stop pursuing rank and they will stay at the belt or level that they're at for the rest of their career.
I think it is really the person and not the beginner, intermediate, advanced rank, that determines who's is concerned with rank or not.
From my own experience teaching young kids through adults, most kids want to move up, their parents want them to move up (be tested and show outward progress by a new belt), many adults do as well. Even my black belts want to know OK what do I have to do to earn 2nd black and so on.
However in my classes we don't have belts on the wall to stress that idea, we don't wear stripes on our black belts to denote rank, we don't have our names embroidered, or anything really to make it special. It's almost down played.
At my instructors home dojo where I trained, it took me 8 years to earn 1st dan, then 7 yrs later I tested for 2nd. We didn't wear belts when we sparred or worked out there, our ranks really only mattered outside of the dojo in other training halls (cause that told us where to line up).
One of the guys who trained there technically stayed at 1st or 2nd dan level by way of kata, basics, you know that type of skill; however he sparred and trained with the rest of us and he had been in it longer than most if not all of us. But he was in it for fight, the friendship etc. etc. he didn't care about the rank per say. (He was/is highly skilled at sparring (kick boxing type) so he was way beyond the 1st/2nd dan rank in the sparring skill wise.) This guy over the years was promoted with the rest of us, I'm using him as an example of someone who got to a certain rank and what was beyond that rank didn't really matter, but he stayed in for the training.
So in my school rank is down played to a degree and I don't pump it up nor really worry about it, and yet my students do, even my black belts. But again I've had some students come and train with my Modern Arnis class who have trained before and don't care about ranks or belts either.
Well the thing is, if you do train at a dojo that has ranks, if you stay at a low rank for too long it can cause complications. With higher ranks its not such a problem but staying at low ranks overly long can cause complications with the training.
Why? I guess it depends on the school. At my instructors commercial or open dojo he has an age requirement for 1st dan of 16. So students if they start at 6 yrs old might be in the school for 10 years before the test for shodan. It doesn't mean their training was hampered just that by then they are really good 1st dans. He has requirements and you bend to that requirement period, one of them being age for 1st dan.
Likewise (speaking of my school) if a student decides they want to only stay at a certain level then 1) they can stay at that level and not move on past it, 2) bend to the will of the instructor and learn the requirements to move to the next level, or 3) maybe the school (like in my Modern Arnis class, or as the case was in my instructors home dojo years ago with the guy I referenced above), doesn't really care and proceeds to teach them further skills but not really worry about teaching by a standardized rank orientated curriculum.
I don't see a problem.