When a human is creating files by hand, I almost certainly agree. When a program is creating files, however, it's only a matter of time before weird characters wind their way in there.
I really wish newlines had been disallowed. (There's UI implications, in addition to the parsing ones — how do you do a list view with newlines in the filename?; I also wish filenames had a reliable character set and weren't just bytes.)
Someone replied on LWN, when he posted his proposal, that he had implemented a sort of home-grown database using non-UTF8 characters for the file names.
Rube Goldberg, indeed!
Show them with the standard escape sequence for a newline:
This\ filename\ncontains\ a\ newline