I don't get how this battle on its own in any way shows Daenerys is a monster. I mean, do think a bit.
1. She is losing and has 3 of her allies pretty much completely out of the game. She needed a hard hitting weapon to retaliate and she brought it.
2. This isn't a village. This isn't a city. It is 100% a military target on an open field close to nothing. Not a single regular civilian present.
3. Dothraki on an open field may have an advantage but having a cavalry charge (without armor!) at a completely covered and firm spear line would cause a ton of losses. By attacking the small patch of Lannister soldiers with fire she created an opening for the Dothraki to safely go through and the Lannisters couldn't cover or reinforce that space because... fire. The whole scene also probably demoralised the Lannister soldiers to the point where a regular Dothraki charge could do a lot more damage at the rest of the line.
4. From that point on, unless being directly shot at, Dany focused the fire almost entirely on the caravan and the supplies. The few soldiers that stood right next to the caravan were almost entirely a collateral as they were not the main target. If you see the angle at which she is flying down to the caravan, you can see she could have just as easily burned the entirety of the Lannister line without any problems. SHE DIDN'T. She specifically chose non-human targets.
