The debate of him being a legend or not should be taken in some years from now , when his career will be over and we'll get true insight on everything that happened with him :-/
My opinion in Vidal's situation is at is stands , is a mutual agreement , both player and board decided it was best for him to move on , but what bothers everyone is the fact untill a couple of months ago he was stating he wants to end his career with Juventus and now he is away sayin 'forza bayern' , ofc some get iritated with this and as i saw around here some people are too harsh , VIDAL was a 'fan favourite' in the real intent of the word , he was the guy tatooed with Juve stars , the one sayin how much he loves the club publicly , that is a the kind a guy who will leave a bitter taste to probably everyone , as much as the official version is that he wanted a move away.
Let's take it this way , from my view on Marotta-Vidal down the years , the situation might also be like this:
Vidal was happy here but in the past months he probably wasn't threated that well , Marotta having good reasons to be pissed at him , the last time in 2014 i remember Marotta giving a ultimatum to Vidal after his bar/brawl incident and being fined the highest ever fee from Juventus. That says a lot! Giving that his performance decreased after that incident and it wasnt untill march when he regained form. Mainly is that our Board doesnt feel impressed of Vidal's "extravaganza" and kinda decided to threat him more "manly" , this probably was the main upset for Vidal and given the fact his lifestyle may not prevent him from doin something "naughty" again , was better from his point of view to step out now , probably with a glimpsering of hope that Marotta would somehow beg him to stay or something like that , which of course didnt happen and was sold. Nobody really to blame , Agnelli and Marotta have the duty to protect Juve's image and self-esteem , as Vidal is a South-American player it can easily be understood that this was a mutual yet not so friendly agreement on his departure.
You guys can also google what i sayd here ... and if u read some combined news urselfs can see this is probably the main reason it all happened.