You just summarized (though subtly, perhaps unintentionally) the narrative Rossi provided his fans to echo, which they have been. However, let us be clear, Rossi did NOT switch manufacturers because he wanted to take on some 'heroic risky challenge'. He did NOT do it for some honorable reason, quite the contrary, it was over a lack of character!
Rossi left in a fit of ego because he demanded all the control, credit, and preferential treatment. Honda wanted to point out they were responsible for engineering a great machine (how mean of them) Yamaha at the time wanted to offer Lorenzo equal support (a crime, i know). Rossi saying "it takes balls to switch" is ........, he didn’t switch for that reason himself and was clearly trying to goad Lorenzo. I don't believe Lorenzo left Yamaha over goading. I don't believe he was too affected by Rossi's ongoing petulant behavior, the problem was his employer not only allowed Rossi to foment dissonance but worse Yamaha contributed to the debacle by publicly backing up VR for an indefensible act. I don't believe Jorge left over money, a new challenge, or to prove something he had already proved at Yamaha (like Julian Ryder hypothesized on a whim in coach, and I'm sure the message will be echoed by his colleagues); I think Jorge left Yamaha because he places human relationships who conduct themselves with principles for life, such as honor, respect, honesty, and fairness above other tangibles.