Recently I saw Linus’ post on Genome 3.4, where he was complaining that it is hard to make fonts smaller. This reminded me of my recent experience in installing Mint/Ubuntu under a virtual machine. I have exactly the same problem. In Unity, I wanted the font to be smaller, but I found I have to install a 3rd-party tweak tool that is not part of Ubuntu. I deleted the VM immediately.
Linus blamed Gnome not being customizable enough. I blamed Unity, too (in Xfce, it is easy to change font sizes), but I think a more fundamental problem is the default setting of Gnome3/Unity/Xfce. On Mac, I am happy with the default system fonts and font sizes all the time (I changed font settings in a couple of applications). I have not heard that a Windows user complaining about the system default, either.
No matter how fancy a user interface looks afar, if the fonts are ugly or in the wrong sizes, it is a complete failure. Why haven’t those UI designers realized this simple fact even till today? It really amazes me how the UI designers can live with such a big ugly font size, and they love such ugly fonts so much that they even disallow end users to change them!
Sorry for the rant.