i wouldnt really use med'an as an insult to half races.
half races are okay, i wouldnt say they are boring, rexxar is one of the coolest most popular characters and hes a half race.
me'dan wasnt awful because he was a half race, he was awful because he was a huuuuuuuge mary sue.
oh i can use all forms of magic and my father was like one of the most powerful beings in the universe and oh my grandma actually wasnt dead and im the new guardian of the universe with my team of super cool pals