Community input counts.
Now while Ubuntu has a fantastic support community apparently community input on over all design does not matter. Do I think it is right? Not really, but it's their product so Shuttlesworth/Canonical has every right to make executive decisions such as these.
The creators of Linux Mint show a very different mentality when it comes to community input and the design of their Linux distro. In fact it is not uncommon to see popular suggestions that occur in their user forums to become a part of the next Mint release.
A recent example of this would be the Mint software installer. Built from scratch the Mint software installer was designed to be a better tool than Ubuntu's old Add/Remove programs for users to install software from. Then the Ubuntu Software Center released and put the Mint manager to shame. With Mint 9 the Mint Software manager has again been rebuilt from scratch to feature the best qualities from the old software manager, gnome app-install, and the Ubuntu software center.
Now what is the big deal about a distro making improvements to itself in a new release? It is the fact that the creators took to heart what their users where telling them when making this improvement. For some of you this may not be a big deal, but personally I enjoy using a distro where my opinion counts.