I agree. In the (upcoming) age of high DPS screens, I'm finding the default font/size to be quite thin and small. We could do with a thicker font, or the current font being bumped up a couple sizes.
Not so much for the font used in forum posts, but just about everywhere else. Such as the "Quote" links in the top right of each post, or the "breadcrumbs" links at the top of the page, etc.