Distributions, or why Universe matters
Most of us know what makes open source software better than their proprietary counterparts. However I would like to stress one purely technical advantage of Linux distributions when compared to their proprietary alternatives.
It's the concept of distribution. Making software for your platform available from a central repository, with installation, upgrades, security updates and removals all done by the same set integrated tools and processes.
Having been forced to use Windows professionally in the last years, I have been reminded of how great that is. Long-time distro users tend to forget. The whole process of hunting down software, selecting something that is less likely to contain spyware, downloading, installing... it's so complex and boring. And then, you have to follow each product security advisories to try to stay up-to-date security-wise. And then, all those separate auto-update services run in the background. And then, when you try to remove the product with its specific uninstaller, you realize there is not so much incentive for software publishers to allow you to completely get rid of them.
So distributions, by making selected software simply available and upgradeable, are invaluable. The corollary is that you need to have enough software available through your distribution that people don't have to manually install stuff, otherwise you're back at step one. I remember switching from the old RedHat to another distro because I wanted exim and they forced you to run... sendmail.
That brings us to my second point: why Ubuntu Universe matters so much. A distribution is a lot less interesting if you can't find what you're looking for it its repositories. Thanks to its strong Debian roots, Ubuntu inherits from the largest package base. But we also need to ensure that those packages are working properly, are easy to deploy and integrate well with the rest of the distro.
Having recently been accepted as a MOTU, I'm proud to contribute wherever I can to this goal. The package wealth is the core strength of a distribution, and this is why taking care of the Universe matters so much.