Hi Alex, there is an option you can set to use thinner antialiasing, see here for more information:
http://moi3d.com/forum/index.php?webtag=MOI&msg=5961.2

I'm sorry but I don't really view the look of the icons to be very significant, it's just not something that is a priority right now. It is possible to customize them yourself if you want by editing the PNG files in the \ui sub-folder.

Filleting is something that I would like to improve in the future but I'm not sure when it will happen, there is a lot of work involved. If difficult filleting is a priority for you, some other CAD program would probably work better than MoI for that type of use.

- Michael