There is no point supporting .rpm and .deb in the distro. The point of packaging is to be consistant in scripts, dependencies, etc. The archive format is not that relevant. Suse and Mageia and Fedora use rpm, but the packages are not usually interoperable. Ubuntu, Mint, Debian have somehow compatible packages, but it is not because of the deb format, it is because they are all Debian-based and follow its policies.
To answer your question, this is the job of packagers like me to take upstream software and make it into a rpm that will work for all Mageia users in a convenient way. Some upstream projects propose some packaged version of their software, either in rpm or deb, but it is not recommended to install those, as they usually cannot keep up with every distro out there. In short, it's not because it's a rpm that it is going to work on a Mageia, Fedora, or Suse system.
By the way (and to confuse you), alien (conversion between rpm and deb) and apt-get/dpkg are in Mageia repositories :-)

Well, we would love to welcome you in the packager team!
We run an apprenticeship program to get you up to date with our infrastructure and policies, and off you go, adding and maintaining packages yourself for the benefit of all!
Otherwise, please open bug reports in the category "new package requests", so that we know what is missing for your use. Cheers!

As a Mageia packager, I can report that it was indeed really fun and enriching working on Mageia 3.
We have to thank the whole friendly community, which provided code, tests, reports, fixes, documentation, translations, comments and donations. Our goal is to make a great community distribution for everyone, with an emphasis on the ease of use and on empowering users and making them part of a community.
We hope you'll like it if you give it a try!
Now let's start the work on support and on Mageia 4.

"PS. I know nothing about France."
Reading the comments on Slashdot, you aren't the only one...