I really can't sympathize for any of the things you think GRRM robbed you off, or agree with any of the conclusions you are drawing about the story. Obviously we all have our own opinions, so if that is how you feel there really is no point in arguing, because I doubt anyone's going to change your mind if they haven't already.
Again, we are here to discuss the books, not to simply dismiss someone's opinion because we don't like it. If there is no point in arguing or debating, then don't bother to say so. The OP is making an interesting point, and one that 5 pages of posts indicate is important. If a person wants to be a GRRM fanboy, this is not a forum that will let you do so without a cost. GRRM is a brilliant writer, but like the rest of the human race, he has his faults, and they inevitably come out in his writing. ASoIaF is not perfect.
I can sympathize with the OP, and this from an avid fan of this series since I first saw A Game of Thrones on the shelf when it was first released in the late 1990s. I also liked U2 when they released "Boy".
Kidding.
The OP (with an almost impossible username, jaomadeira1000?), is upset at the manner in which the Stark v. Lannister storyline was ended so abruptly. The argument is, as far as I understand it, that a lot more mileage could have been made from that dispute, but The Red Wedding made that impossible, destroying that story arc. Could the story have been better had TRW not happened? Truthfully, we'll never know.
I do remember feeling, as the Imp posted above, like Gregor Clegane had punched his mailed fist into my stomach (great metaphor, Imp). I also think that the Stark/Lannister conflict could have been explored at length. However, that is something of a red herring, and perhaps there is some fan fic out there that speculates on what would have happened had the Stark host not been massacred at the Twins.
However, I also encourage the OP to continue to read the series. The Starks are not done, and neither are the Lannisters. I would not be surprised to see an accounting before the end (Arya Underfoot, anyone?)