My guess is that they've looked at Free-to-Play business models like Quake Live, Team Fortress 2 and Tribes Ascend (which has done well despite still being in beta) and decided the Unreal Tournament brand would be perfect for a continually profitable F2P product.
This would allow them to profit while still in beta, while also empowering them to iterate their beta with feedback from the community.
Despite the skepticism you might read in a hardcore fan forum like this, I think there's an installed based of loyalty to the Unreal Tournament franchise that could make this model work great for them.
(1) Based on brand recognition, high press visibility and brand loyalty, they could probably break even or maybe even profit before they're out of beta.
(2) Based on the number of people who still visit forums like these or who still play the original Unreal Tournament nearly 13 years later or UT2004 nearly 8 years later, I'm guessing they won't find it hard to harpoon a few "whales".
("Whales" in the F2P market are customers who, over the course of their time with the game and through tons of microtransactions, end up spending way more on the game than the standard one-time purchase price of a game. So you make $200 over 25 months with several small transactions compared to just $49.99 in one single transaction.)
The benefit to us would be that this would inevitably be PC-centric.