Do I find television worthless? - No.
There are shows I watch for entertainment and some for either learning or keeping updated on current events, so I find some worth in it.
Do I think I'm paying more for for it than its worth - highly probable.
There are (were) 3 shows I go out of my way to watch (BSG, Fringe and The Mentalist) and a handful of shows I enjoy watching but could live without (Mythbusters, Digging for the Truth. Ancient Discoveries, Dollhouse, Lie To Me and probably a few I'm forgetting (which shows their importance)). The news I can get from radio or on-line and probably be more informed, but I do enjoy the lazy factor of being able to get home and turn on the TV to get a basic overview of current events.
If I were to quantify what I spend on cable and just allocate it to buying the season DVDs of the shows I like when they are released, I may actually be better off financially, but aside from the waiting issue, if I and everyone else were to do that, the ratings would plummet and the shows would probably get canceled (despite being a great show Firefly did not get good enough ratings to sustain it beyond its first and only season, so I'm a bit paranoid about favourite shows gettign canceled if they don't get good ratings). I think eventually the distribution and compensation model for television will change in the face of its pending obsolescence, but for now willful resistance of the existing system is not advantageous to continuing the life of my favorite shows, so TV has worth in the sense that without it, stuff I might enjoy watching might never see the light of day. - not being a nielson household, I know what I watch or do not watch does not actually matter, but its the concept extended to assume what might happen if those that are did that.
Beyond how it affects me directly, I think there is also great worth in TV if a show like Numb3rs, Mythbusters, or any show on The Discovery or History channels inspires someone to want to learn more about math, science, history or anything else. Another value some well written shows have is to reach the masses with ideas that they might not be comfortable digesting in a news or debate format - by framing ideas in a different entertainment based context they can be put on a more neutral field so that one is more likely to look at it objectively and see multiple sides of the issue.