It's tough to design something that fits into their collection. A plain pattern won't stand out of the crowd enough to win. A complex pattern will probably get dumped for being too hard to make, and too hard to adapt. Designing a pattern isn't like designing a garment; you can't rely on a particular fabric or trim as a design feature. The design features have to be in the construction itself.
I've been sketching patterns for the contest today, and it's challenging to design a garment that's versatile enough that people can make it in their own choices of fabric and - this part is great - so they can remix the pattern and make something different out of it.
BurdaStyle actually makes a big deal of their patterns being "open source" - they encourage people to download the patterns, modify them, and share their modifications. I think that's really cool of them.
(Arguably, clothing designs aren't copyrightable in the US, but just try telling most pattern companies that.)