It's not her attractiveness...but her divisiveness (ironically, as a woman who consistently accuses others of what she herself does) & her overall lack of education in both postmodernism & civics, political science, geopolitics, micro/macroeconomics, and most of all: foreign policy.
Ironically what you're saying is that she isn't taken seriously because she's young, powerful, and attractive is in itself extremely sexist through flagrant pandering & virtue signaling...
People don't hate on her because she's beautiful & powerful.
They hate on her because she's vastly misguided & uneducated, with power.
I'm trying to be nice here...some would call her straight stupid. A "useful idiot" if I've ever seen one, yet 'insults are the last refuge of the ignorant' - Socrates.
This is all my humble opinion in an effort to encourage civic dialogue...not a "I'M RIGHT, YOU'RE WRONG! WAHH!" type of post -- just to be clear, for anyone who can't discern from the subtext.
I encourage those who disagree to reply & explain why.
There's nothing better than healthy dialogue & besides, think of how boring the world would be if we all agreed =)