I agree with you, with a few notable exceptions. On the shitty side, most of them suck for the very reasons already posted. They generally have low budgets and are made in a hurry. This is not conducive to getting top quality talent involved.
I think the newest made for TV movie, Saving Jessica Lynch, is going to miss the small pile of quality and land dead square in the massive pile of crap. I will admit I am curious to see how they treat the battle where she was captured because I don't think she can remember any of it. The other problem is, did anyone see the previews they were showing on NBC all night? The end bit, where they put up the words "Saving Jessica Lynch" is ripped right of the box from Saving Private Ryan. Next time the add is on check it out. I'm halfway surprised NBC didn't just call it Saving Private Lynch instead and just get it over with. BTW, none of this is against Lynch. NBC made the movie, not her.
As for the exceptions, no other network has done the job with miniseries projects like HBO. From the Earth to the Moon was amazing. A really high quality job. I think it was unsurpassed right up until Band of Brothers came out. There is really nothing about either series that would make you think they were anything other than really long movies. All the actors, directors, writers, special effects, and stories were excellent.
I think the difference is the people driving the projects. In both cases you had Tom Hanks intimately involved in the project. In Earth to the Moon he was working with Ron Howard. Band of Brothers had Spielberg.
Those kind of names, when they have a real passion about the project, make a lot of difference in how it is executed. Saving Jessica Lynch lacks the names and the passion. Of course, what do I know, it could be excellent.