But George RR Martin is a sadist, and he said he likes killing characters people like. Besides i said caring too much about your characters. I'm thinking along the lines of Gaias from Battlestar Galactica who should have died in season 2, but got carried to the end of the show (in season 4) so on, so on.
And on the note of television, a Song of Ice and Fire was a direct retaliation to the executive meddling and production constraints GRRM had experienced in his 30-year career as a tv-writer. When he sat down to write A Game of Thrones he set out to write sets as expensive as he wanted, as extensive as he wanted, and he could kill whoever he wanted. You'll find he's not nearly so "sadistic" in his other fiction, and certainly not in his television writing (excluding of course the episode he wrote for Game of Thrones on HBO).
Actually GRRM said he put off writing the Red Wedding scenes until the rest of the book was done because it was so painful to do.
Once you've jumped into television, though, that's a whole different ballgame. It becomes about what the producers think will sell or what an actor is willing to take a contract for etc, etc. It's not about whether the creators care about the characters or not; it's about what will bring the money in.