Unicode isn't even hard: Use UTF-8. Don't try to measure the length of a string unless you're rendering that string and measuring the length in screen units like pixels. If you do those two things, that's 90% of the effort of making Unicode-safe software.
I think both views are valid. Those who don't know how to write Unicode-safe software shouldn't feel shamed into learning Unicode before releasing open source work. Those who already know Unicode should feel happy that they're making other people's lives easier.
As far as I know, UTF-8 will work 100% of the time, and is almost always the best internal representation for software you write due to how simple and uniform it is. If something is encoded in some other format, you can probably find a conversion function online.
I'm not saying that it's really all that hard, but there are multiple document formats, and versions of those formats. The author obviously didn't need unicode support, so didn't test for it. I'm sure test cases, and a pull request would be welcome.
In ten years it might be better.