The newer unity versions have so much larger text than in the past, that some players from the older versions actually complained about it a bit -- there's definitely not room on smaller resolutions to have the text any larger, and playing at larger resolutions and then increasing the font size would just make it look like the smaller resolutions but with the actual ships and game icons rendered in a tiny fashion. Given the technical challenges Keith noted, and the above, dynamic text sizing isn't something we plan to do (and I can't think of many -- any? -- RTS games I've played where font size was controllable).
At the default resolution for my MacBook Pro with the game (1400x900), the text is slightly larger than the default in Safari, for example. At 1280x800 it's a bit bigger, and at 1152x720 it's pretty huge-looking. Our stance is that you can really custom-tailor the view to the size that you like to a pretty great degree here, just not the font independently of the rest of the view size. That's pretty standard with this sort of game, I also feel.
I wish I could do more, but we also have to work within the constraints of what makes a rather huge UI actually fit on the screen and be testable with a minimum of resolution-related bugs.