No spaces in names?...

Why cant we use spaces in (last) names, and especially so for the tombstones, book and credits?

Many countries have names with spaces in them, and some people have double first names that are either with spaces or dashes:
Jean-Marc
Sammy-Jo
Petronella Maria

Von Amsberg
van der Ende
etc.

We were told we could chose what name to use in there, and that it could be separate from the Avatar and even be our own name, but that would be hard for some of us with these restrictions...