I agree about USV, it creates confusion where none needs to exist. For personal use, though, it is not that bad to receive a USV: it should be postmarked ".usv" and in any case if you suspect shenanigans you can `grep` for the offending (literally!) unicode characters and `tr` them into proper ASCII separators. Now, if there is nesting in the USV, I give up.
I share the lament: the whole table issue was solved before it became a problem. POSIX divides ASCII into portable and non-portable characters; only portable characters are allowed in the fields and separators are non-portable. If you need nesting, use a portable encoding of the inner table. This scheme repeats indefinitely without escaping hell or exceptions, preventing tons of errors and headache.
Visibility is such a bizarre complaint. Text editors already handle control characters: they handle tabs, they handle newlines, it is not a tremendous, earth-shattering feature request to make them handle separators gracefully.