Besides the good points about the difficulty typing characters, not all fonts have good glyphs for non-alphanumeric (by that I mean low ASCII) characters. Sometimes they don't have those glyphs at all and the system has to go to a fallback font. Terminals can also shit the bed with Unicode characters.
The solutions to those problems is to use better fonts, terminals, and editors. Using Unicode characters is fine but some people do have legitimate problems with them.