It's not just the fonts, it's the whole desktop that is a strain to the eye after a while when it's that small.
When using an app that allows resizing then i.e when needing to find a file from the built-in file-chooser, it's too small again. 
It was one of my earliest gripes when Alpha (Beta) came out:
I couldn't use the menu on through the touch-screen 'cause my fingers were too big i.e the widgets too small.
On top,
I don't have any other screens that have a similar high resolution, not even my drawing-tablets (they come at 1920x1080).
So there's nothing I can use as a second screen (yet) without losing some screen area.
