Yeah, it just creates clutter. People should really stop doing this.
A plugin or some filter to prevent spaces from being created.
This would ensure that clutter is not created, and would reduce the load of posts flagged.
There are absolutely valid use cases for spaces (even you are using them!), if you mean characters like U+3164, there are probably still valid use cases for those, such as in scripts (maybe you need a string filled with those for some reason).
Also there are as many ways to bypass the character limit as there are grains of sand on a beach, so it is not scalable to add each one in. You will still find posts with bypasses in the future. The most they are is a nuisance.