To help test applications, I find it useful to deliberately use "UTF-8 heavy" strings in various UI elements such as forms etc.
Having a reverse operation would be handy, so that you could quickly generated those. For example a -r option:
unidecode -c -r "Dick Visser"
Ðĭçκ Ṿĩşšεŗ
Since there would be more than one way to do this, I guess this could be done randomly from a set of eligible characters. Or perhaps a config option to use only specific sets.