Your "Logic" is nothing short of mystifying. I'm not saying you should boo Nash, Marion, or anyone. I love all the Suns myself, and I think a good majority of them are terrific players, including Marion.
But if Nash is more important to the team winning than Marion, something we'd all agree on, why is it "ok" to get mad at Marion and not at Nash for the Suns not winning the title? Shouldn't we be upset at the person who has the most responsibility?
For instance, if Apple Computer doesn't do well for the next year, no one is going to be saying "fire Jonathan Ive" (their industrial designer), they'll call for Steve Jobs' head, because he bears the most responsibility.
In what crazy world do people get upset about a goal not being met, and then say "its ok not to blame the most important piece, but lets blame the foot soldiers"...its just more crazy Sunsman44 reasoning.
All that being said, I don't think Nash or Marion deserves to be 'blamed' solely, or really at all for the Suns failing to win a title. They've had some horribly unlucky breaks and have a great shot this year.