In my view, the primary reason for the curved screen is to visibly differentiate this new TV technology from existing plasma and LED tech.
These concave screens are very different from anything seen before thanks to the nature of OLED. As a result, they provide an appealing and easy way for the mass news media to highlight the arrival of this new technology to Joe Q Citizen, wihout getting into talk about contrast ratio and cm/2 ratings.
These sets aren't meant to sell in any numbers (and are priced accordingly), largely because they're obviously still working to produce panels in a reliable and affordable way.
What they do is serve as a flag in the sand, saying 'OLED TV actually exists, sets are now available for sale, this is the future'.
It buys the companies a little bit of time, and plants the seed of OLED in the public consciousness while they work to develop the manufacturing process.
The problem is that OLED is going to have to come to market pretty cheap early on. Plasmas may have been $15,000 when they came out, but they represented a radical departure in design from CRT and were therefore highly desirable. OLED will be competing against tech which, when seen in a bright showroom, may not look much different in terms of design, and it might therefore struggle to command a hefty premium.