You could be right Dare, maybe McLaren thought they'd found the new Ayrton last year. The luxury of family money and temperament is certainly right.
At least Ayrton was never in line of fire from his team, I haven't found anything else than admiration of his work ethics, from his team members, engineers & crews. I think that is a stark contrast from the behavior of Sergio, emerging in the media. Even Sebastian Vettel, the arrogant, single-minded, win at any cost attitude person does not mess around with his engineers.
I'm not aware that the McLaren boys who engineered Sergio's car, or even the team, have complained of his work ethic - or even his attitude.
Martin has since explained that another team boss, not one of the two back markers by the way, had let them down by promising a seat to Magnussen for next year, shaking hands on a deal and then later welched on that deal.
This left McLaren in a dilemma, break a promise to Kevin who they rate highly, or not take up their option on Perez. Maybe in time we'll learn just who reneged on the deal.
I'm sure there are more than a few who failed to warm to Ayrton's personality, however when you are clearly gifted and then start winning people put up with more. Now of course the 'don't speak ill of the dead' mantra rightly glosses over things for everyone.