Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
It has been some time since Ubuntu introduced their App store interfaced 'Ubuntu Software Center' geared towards new users featuring one-click app installations. I'm pretty sure the Software Center did play a major role in convincing some Windows users to turn to Ubuntu.
Unlike Windows, they don't have to hunt for the latest software packages from the internet or illegally copy it from friends. The Software Center in Ubuntu itself features around 33,000+ packages ready to be installed in addiiton to other third party applications compatible with Ubuntu available from other websites.
Actually the concept of a Software Center isn't new to the Linux world. Most of the Linux distributions have a well maintained software repository which contains only packages approved by the maintainers, so reducing the security risks on users. What Ubuntu did was to craft a custom new user front end for this repository. And it won the race in pulling in new users too.