It's what I do. I don't have cable, but with all the legal streams out there it doesn't bother me that much. I watch TDI on Cartoon Network's Video site, Colbert and the Daily Show on Hulu and Conan on NBC's site, plus various other cartoons and shows that are available when I feel like it. There are a couple of holdouts, like The Soup, but if you really want them you can get most of them on iTunes.
I much prefer the seeming rise of legal, free streaming. It doesn't have that icky feel or low quality that getting the stuff illegally sometimes has. And although there are unskippable aRAB they are usually pretty short. I would prefer that company's not so agressively region lock their content, though. I tried to check out some world cable networks but a lot of the shows were blocked.