Sony is a massive company. Based in Japan where it was founded the company consists of many different divisions, each handling a different electronics market segment. Among its most successful divisions are the Playstation and camera ones, consistently pulling a profit in almost any given quarter. One division that hasn't been fairing so well for them is the mobile division responsible for the Xperia lineup of smartphones and tablets, which has been dragging the company down as R&D and manufacturing costs outweigh sales of the many devices Sony makes. Many blame this on the constant incremental flagships Sony puts out every 6 months or so, doubling the output that most smartphone manufacturers update their flagship lineups.
While build quality and software is pretty universally lauded for every Sony phone, the camera is more of a hot button issue with Xperia devices. Some users swear by Sony's experience given the gorgeous 60fps viewfinder, advanced software with a boatload of features and overall solid image quality. Others rag on it for inconsistent image quality, heavy denoise filters and overall poor low light performance. Either way you swing it Sony has had one of the most advanced camera interfaces for years now, offering more features than most manufacturers would ever bother thinking about. While the Xperia camera software has had a manual mode before almost any other manufacturer out there, there has not been RAW support at all and that doesn't seem like it'll be changing any time soon.
Responding to a forum post on the official Sony Mobile forums a support representative said that under Android 5.x Lollipop there are three different ways for camera software to operate. Currently Sony's software operates under the legacy mode which does not allow for RAW support under the Camera2 API rules. Because of this Sony has written off the feature but says it will consider adding it if enough demand is made for RAW support. For those not in the know RAW support provides ways to significantly enhance a photo via post-processing through specialized software on mobile devices or computers. Professional photographers swear by RAW shooting as it allows them substantially more control over the photo making experience, taking even photos that began as useless and generally turning them into something special. RAW isn't a magic wand by any means but it's probably the most powerful tool in a manual photographers repertoire, and it seems only fruitful for Sony to support this mode for enthusiasts. Head on over to the forum below and sound off to request it!