I don't get it. I hear/read things all the time where people will say, "If you don't like what a company does, don't buy their product." But when people finally decide to no longer support a company, in this case BioWare/EA, all of the sudden they're whiners that have taken things too far. Must be a timing thing.
As for the 90+/100 ratings the game got, I see it like going to the best restaurant in town, and enjoying one of the best meals ever only to have the manager say, "I hope you choke to death on your spoon a--hole." while you take your last bites of desert. That's how the ending to ME3 felt to a lot of people.
Trust comes into play in all corners of the consumer/producer dynamic. If a company builds a reputation within an industry of making a quality, solid product, the customers expect the company to keep dong that. Most companies strive to achieve and maintain that level of trust with consumers. That way it's easier to introduce new products and keep more money flowing in. Paizo and Pathfinder are good examples of this dynamic being done right.