Why would anyone want information services or casual games (apart from those to be played with others in the room) on the big screen rather than the phone/tablet?
In the pre-iPhone case there were lots of people wanting information services on phones (on the move especially) and people trying to provide solutions greatly limited by available technology and bandwidth prices (no wifi on phones at the time either). People were trying to read books off phones, listen to music and do many things including some apps even when the capabilities were extremely limited.
Its really not a people don't want argument but TV prolonged screen interactions don't generally fit into people's lives except in a very few narrow scenarios watching, sharing and showing content. In all these cases controlling with a smart controller and interacting offscreen really works better than indirectly manipulating a bigscreen GUI.
If we imagine a TV with unlimited computing power what would it be used for? Well it would replace games consoles. It would offer smarter ways to find content (but the availability of content is probably at least as important) and better search isn't generally a game changer in this market.