It's depressing that this is such a common argument against moving away from the ASCII character set. We all use operating systems that allow us to define key sequences for these characters. And it's really easy to remember them after a week or so, I mean, how often do you actually look at the letters on your keyboard anyways?

The main issue is that computers don't come with a standard default layer for math and APL characters anymore so it's a huge leap of faith for someone to start to use these characters.

I had to paint my keyboard blank to learn writing withot looking at the printed on symbols ...

In Emacs and other editors you can use a special prefix symbol (typically they use \ like TeX) and substitute the special symbol for the word.

  \in => ∈
  \emptyset => ∅

This allows the user to type in using an input mode they're familiar with (standard text), but get an output that looks better (IMO).

> Typing these characters is quite annoying though

This depends on the implementation. In Dyalog APL for example, the special characters (glyphs) are effected using fairly simple two-key sequences. Mnemonics are used to help learning. I found it fairly straightforward, surprisingly so.