You don't want to build too much into the TV. Consumers tend not to want too much built into their televisions, and the technology for a television doesn't move quite as fast as the technology for the external devices that are going to help you manage all your entertainment.
While aggressive competition between retailers, OEMs and component suppliers as well as the holiday seasonal rush helped spur this (price) decline, ... The most prominent culprit was the rise of sub-$800 computers.