First, I agree with you about the teenager part. Most of the posters on here hated having any adolescents on the program. Second, it was also shown in Canada and I believe (from some posters mentioning it) that it was shown in Britain also so it wasn't just on American cable TV.
Third, I think you underestimate the huge percentage of sci-fi fans who only want "progressive" futeristic settings, space battles, aliens and mindboggling technology. These persons trashed BSG and Caprica and espicially the series ending of BSG for that reason. They couldn't stand that they had telephones with cords instead of communicators, used cannon shells & machine gun bullets instead of phasers & photon torpedos, dressed like 20th century humans instead of running around in tin foil suits or outlandish costumes and that there were no purple blobs or pointy eared aliens. If your program don't adhere to their idea of "sci-fi" they do their best to get it cancelled. The intolerance to other concepts is almost Stalinist.
I enjoyed the first 2 seasons of BSG it was when they "gave up" and decided to stay on the planet where the cylons caught them is when that show went downhill in my book. And I get the corded phones and cannon shells and all that of Gallactica as it was the older model and with the twelve colonies essentially at peace there really was no need to develop advanced space weapons. But what doesn't make sense is you just landed on an alien planet with the last (what 20k) survivors of the colonies would you atleast dismantle the ships to use as raw materials to build shelters that would give them the best chance of flourishing? and I had already guessed the basic path of seson 4 that the mid point we would get to "earth" and it would be destroyed and we would move on and find another planet to call Earth, the only question and it was answered in the final minutes was when relative to our time was it. The thing most people or at least me that didn't about the ending was the reason that Adama chunk the ships into the sun, and that is this Idea that technology will destroy us as a race, and that is a debate I just don't feel like having right now.