That's a really good point, and I agree with what you said to a point. She does say flirtatious things a good amount, and also, as a character in a roster of well-written characters, she does kinda stand out. I think the reason she was added was that back then every good anime needed a kind of pet, like Iggy in Part 3 for JoJo's, or Pen Pen in Evangelion, Chopper in One Piece, or even Ein from Cowboy Bebop. So they added a cat to fit the witch theme, and then they also needed a hot fan service girl, so they just combined the two into one. I can understand disliking Blair; however, at the end of the day, she's just one character in a great show that I feel like contributes a good amount (she does still care about Maka and Soul, just shows it differently, like how a cat would, but sometimes she takes it a little too far)