@cloudforest: Wasn't part of the whole delay with Dance of Dragons because he couldn't figure out how to get the characters where he wanted them to go? Seems like his biggest problem has been knowing the ending but not having clear beats he has to hit to get there. He just writes then realizes "crap I want to get to point B but I'm written myself into a hole"
This has been my main issue with the series since about season 2, but I know it's an issue that originates in the books. They build up to large, world changing events like Stannis taking Kings Landing, or Robb moving south, but both get cut short, and everything else moves on practically unchanged. King's Landing has been exactly the same before, during and after the war. Only now with the Sparrows is the atmosphere of King's Landing any different, but that will probably get sorted out this season so everything can go back to normal.
Even with Oberyn, they build up to this guy, clearly opposed to the ruling family, having large political clout in the city, but then he just dies. In all these cases, it seems like GRRM let characters and situations naturally evolve for a time, then realizes "oh crap, if this plot advances naturally any more, it messes up my plans for the conclusion 5 books from now, I better stop things from getting interesting before I'm ready. I know, I'll kill people off for shock value, to show how edgy and harsh this world is"
Ned's death was good, it set off the entire plot, caused massive changes within the world, it made sense. Tywin's as well, made sense for where the plot was going. Everything else seems like it's just been used for shock value, or to prevent things from changing. Jon's plot seems to be the one that advances steadily, but it does advance slowly. It seems like every other plot that doesn't reach a sudden, shortsighted conclusion has to suffer through filler and delays just so they all reach the right place at the same time for whatever big conclusion GRRM has planned.
On another note, regarding sudden pointless character deaths, I think Bronn is next, as much as I hate to say it. He's doing the whole one last job, getting ready for retirement thing, isn't plot critical, and they probably want to show how badass the Sand Snakes are even though they are the exact opposite. Like Barristan, it will have little to no actual ramifications, and will happen because the show runners just want to shock the audience by killing another fan favourite. And this is a shame, since King's Landing/that area of the story has been hemorrhaging most of it's best characters over the past 2 seasons, and Bronn is probably the best secondary character/sidekick in the show. Seriously, pair that dude up with anyone and he'll give you some great scenes.