I don't believe TV is wrong, as long as we are not watching something completely immoral, or possessing a basic worldview which is the opposite of Biblical principles. I'm very careful about what I allow to come through on my TV, and I have ended up shutting things off on more than one occasion (starting to watch something that "looks good" until well into the movie). The rating system, although the concept is good, sadly isn't very helpful. Two programs can have the PG rating, yet one can be moral, and the other totally opposite. Also, I believe big issues can be touched on in a G or PG show, and still be handled in a tasteful manner.
Also, it's easy to nitpick and find things we don't believe in, even in the most innocent programs. In "I Love Lucy", there was cigarette smoking and lying and deception. Yet, I don't see anything wrong with the show because we have to realize this is mainstream TV that shows the things that happen(ed) in the world. The humor is clean and harmless (unlike some of the garbage today), and many Christians will admit they will watch it over other programs. I even sometimes watch it.
I'm also aware that there are some who choose not to watch any TV, nor do they even have one in their homes. That is a conviction to be commended; for these particular individuals, it is a stumbling block, so it's probably better that they abstain from it. Anything to help in our own individual walk with the Lord. However, everyone's different, and if we think we are doing our best to serve God, that's what counts.