As a Barca fan...
Barcelona doesn't owe anything to Messi. Barcelona took a gamble on him in 2000, while his beloved Argentinian teams refused to fork out the money for his treatment. It made Messi what he is today: a very rich individual, with a system adapted to his needs, with fellow footballers that feel the need to pass to him instead of going for the goal themselves. Barca kept Pinto because he was his best friend, moved Ibra from his favored spot, didn't allow him to be substituted for a long period of time, even took the gamble and brought an Argentinian coach from his own home town.
Now, you might say Messi repaid this in full and I agree. But this doesn't work when one of the two parties begins to take advantage of the situation, as Messi does at this moment. Leaving aside all of the spewed bullshit, Messi is in a clear decline. While his stats are still respectable by any world-class standards, his general attitude, play and interest aren't that good. Having a bad day is nothing spectacular; but not even trying in the games that would define our season is something I can't defend. Forget the team's performance; Messi gets that much cash, that much leverage, that much influence and that much say in the Barca universe because he is supposed to be THE BEST. Think about that word: it doesn't mean goals or assists, it means the belief of others that he is the best. In 2010 all he got was La Liga while others conquered the World Cup or the Champions League; he still received the Ballon d'Or because most of us thought of him as being the best there is. Ronaldo scored more goals in La Liga in 2010/2011; did we say: hey, Ronaldo must be the best player in the world? I sure didn't.
Yes, goals and penalties are important. Yes, Xavi, even possesion is important. But they are insignificant compared to the team's performance. We might like or not Messi, Fabregas or Neymar; but at the end of the day we're all Barca fans and all we care is the well-being of the team. Messi's records are nothing to me; some people enjoy him breaking Barca records as if the Rivaldo or Cesar Rodriguez were the enemy. They were Barca players, too and their records were our own. If I have to choose between Barca winning a Spanish Supercup or Messi winning the World Cup, I'd choose the lesser trophy each and every time. That's why I don't like how Messi is playing at this moment. And that's why I'm not trying to soften the shock by reminiscing about the good old days or holding the idiotic belief that Messi is somehow shielded from ever declining and that the guilty party must be someone else (candidates: Rosell, the board, Ronaldo, Pinto/Fabregas, Martino... btw, if you're looking for scapegoats, why not his son? Family life changes a person and perhaps football doesn't seem that much important compared to a newly-born baby).
And please announce me when Barca starts cutting his salary or refusing his demands before pointing fingers at Barcelona.
Tl;dr - Messi and Barcelona had a great working relationship. But if this begins to crumble, I'm choosing Barca as my side each and every time.