The whole reasoning behind the obsession is that she is a political figure who isnt ass ugly.
While she isn't the prettiest, she isnt a model either, and politicians aren't exactly known for their looks, so when you see this pretty cute politician (which mind you, is only really popular because of the current events over there) people get all obsessive.
All that aside, the obsessiveness is pretty creepy, but i do admit she is pretty cute.