[tedunangst]

This may not be their reason, but I used to have a password with @ in it. Then I went to Germany and discovered the keyboards there didn't have @ on them. That was a fun time.

[icebraining]

You can usually type some easy combination (here it's Ctrl+Alt+2 or AltGr+2) to get it. It's not like Germans don't write email addresses.

[tedunangst]

If you aren't German and can't log in, discovering such combos is a bit difficult. Once I figured it out, no problem.