With the exception of allowing the torture of a wine seller's daughters (which she did out of grief and anger), in the books, Daenerys' use of violence is restrained and soberly considered. She crucified the Good Masters because they crucified slave children. She burned Kraznys mo Nakloz because he was a piece of s**t. The books even make the point that although Daenerys has taken hostages from every wealthy family in Meereen, everyone knows she won't hurt them, so keeping the hostages is mostly pointless. Using dragons to intimidate and kill people she doesn't know to be guilty is outside her character.
There's also the small matter of her marriage to Hizdahr zo Loraq. In the books, Hizdahr is her suitor and the marriage is a political union that's agreed upon by both parties. But in the show, she informs him that he'll be marrying her while he's on his knees in fear for his life.
Not the first nor the last time this show struggled with the concept of consent.
This isn't a small thing either; Daenerys is doing exactly what Cersei did to Sansa when she married her off to Tyrion. Daenerys doesn't have to be a saint, but when she's exactly as bad as her nemesis, it does kind of muck up her character arc a bit.