Magnifico is not even in the wrong in this

He was wrong for being a white male and saying no to a black female.

It is the typical power corrupts trope. His family and former home country got destroyed, so he is totally afraid of it happening again. That's why he build up the new country and he wanted to protect it. It was never 100% clear why he wanted the wishes really (I first thought as source of power, but this comes only later into play), so it should be basically to take their biggest wish, so they are never craving for revolution (or anything other better). It worked out for him to create the wonderful kingdom, but Asha is also right, that it is not all his to take and not even planning to give it back. He got corrupt, seeing everywhere basically danger, even from a 100 year old man. If he had not been so stubborn, he could have done good for the people (granting them their wish when they latest reach their xth birthday) and still be a king. Instead he wanted to protect it at all cost, even by using a book, he is fully aware of it is not good. He get then consumed by the book and becomes a clear dictator to his people (consuming their dreams, if they just get on his nerves).
This is not the story of any old white dude, but likely any person with too much power.

I just finished watching it and enjoyed it. There’s been a lot of backlash on Youtube, even before the movie was released, from people who assumed that it woud be just one more in the growing list of Disney’s failures.
The script the animators were given to work with could have been far better. In particular, the lyrics of some of the songs were quite cringeworthy. (I’ve seen it suggested that Artificially Intelligence may have contributed to their composition. That’s quite plausible!) Yet the animators did a marvellous job of conveying convincing emotional reactions through the gestures and facial expressions of the CGI characteters.
A lot of people seem to have misunderstood the message conveyed by the basic plot, claiming that having everyone’s wishes granted is not a “good thing” and so in the beginning the king was “right” and that Asha was “wrong” to rebel against him. Those people have missed the point. My interpretation is that in the beginning the king was a “benign dictator” who “meant well” but was infantilizing his subjects. When Asha opposed him he became an evil dictaror. I believe, as did Asha, that the “wishes” (aspirations) of free individuals are things they strive to achieve through their own efforts, not things “those in authority“ have any right to manipulate. The “moral” of the fable has obvious parallels in the real world.