So a few notes
- i'm aware of it requiring a restart.
- saying 'high DPI' is a bit of a misnomer. 1680x1050 could have been considered high DPI 10 years ago, but not today
- I have actually tried raising all the font sizes to 20 and changing all the font faces to something different, and I have yet to see *anything change, much less what I want changed
- This documentation is horrific
http://dev.mysql.com/doc/workbench/en/wb-preferences-appearance.html
It literally pretends to detail what each category does by repeating the name of the category. Which leads me to believe whoever wrote this doc also has NO IDEA what its supposed to do
Comments about why changing a font size would be significant work aside... I am not going to enter your bug tickets for you. I don't work for oracle.
Do a google search -- it turns out this is a very common problem. Basically the workbench is just not the best choice until its ready to be used with modern displays. This should be motivation enough on your side.