Keep in mind Gnome is meant to be easy to use, not easy on the screen real-estate. If you want a minimalist UI, there are a million alternatives in linux land
Arguing that it makes the interface cleaner might seem correct in theory, but in practice it really doesn't seem to hold true. Especially when you compare to OS X, which has an extremely clean interface without any over padding of elements.
And the way Linux renders Segoe UI is ghastly compared to the Windows rendering.
If you want a smaller font size, you're out of luck since the padding seems to be assuming that you're going to have those big 5/20 vision fonts, so your buttons have a tiny bit of text in the middle, and acres of space round them.
Can we have a middle ground for padding? Nor too less, nor too much.
sudo apt-get install gnome-color-chooser
Find it in System→Prefs menu after install
BTW I have always hand tweaked the font, DPI, and all appearance based settings on a fresh install of any GNOME based distro. I am not enraged on the padding issue, but it would be still nice to see optimal configuration out of box.