if you read the books you would know that the "heel turn" the show made up made absolutely no sense for Dany's character and the general non-cynical heroes that GRRM creates.

Subverting expectations and all that.
In a similar vein, why did R'Hollor resurrect Jon Snow, when Jon Snow wasn't at all necessary to killing the big evil prophesied monster?
Jon Snow: "Why was I brought back to life"
Red Priestess: "Your sister is going to kill the night king, and it'd mean a lot to my god if you were there to support her."
And why did Arya get the face-change powers when they had fuck-all importance to the plot? Chechovs Eldritch power.

I could see Dany being seen as a tyrant by the lords of westeros who hate her reforms, but the showrunners confused that with her actually being a tyrant. That would have been a much more interesting story, Dany saving the world and doing everything right and doing the most moral thing and still being hated as a "foreign queen" by a bunch of reactionary shithead lords.

Add to that their idea of a tyrant is "motivated by bells being annoying and the tyranny is killing small folk." Rather than tyranny being stuff like "hey you can't just kill peasants and also you have to invest in the state you're running. Maximum of 4 jousts a year."

Poor girl didn't even want to go to Westeros. That was her brothers thing.