I agree on the Mourinho point you have made; that has undoubtedly created a bias in most United fans' subconscious when it comes to judging Pogba but I'd say it isn't completely unwarranted.
He was our best player in terms of numbers last season, but was he really as good as the numbers show us? Rooney got 19 goals and 22 assists in 13/14, yet the majority of this forum slagged him off for being washed up. He also happened to cover the most ground if I remember correctly, yet we all knew it wasn't the old Wayne Rooney.
I wish I could explain what I feel here, but because of English not being my first language I'm not able to put it into words. I'll try my best though.
Pogba may not be washed up but he certainly played like someone who was. Every single thing he did was just something that was masking a flaw in his play. Most of his goals and assists last season were just useful in papering over how many times he lost possession in dangerous areas. He does/did the same thing as Rooney when it comes to passing, i.e, he chose the Hollywood pass over simple options. More often than not it ended up failing though.
Leaving that aside, I think the reason why the majority of our fan base doesn't want Pogba anymore is because of how he runs his mouth at the media every few months once. A fine example of this is when we were on our winning spree during Ole's honeymoon period last season. Soon as there was an international break, he starts talking about Real Madrid and Zidane. And right after the break we started falling apart.
It may sound like conjecture but that's what most things in football are when you are an outsider. When your manager is constantly praising you, giving you the arm band and saying that you aren't going anywhere in front of the media. don't you think it has an effect on the team morale when you then talk about another team and manager? This wasn't the only instance though, but just one I was able to recall. I do remember a couple of other times when this has happened in the past.
Forget about his agent, what about his brother talking smack and telling how he needs to move? You think he'd do that with Pogba's consent?