Why are the Taunts 100% generic?

By that, I mean why are /t taunts never based on any champions in sight range?

Yes, yes, it's more voice acting and more coding, but it would be so much cooler if there were a few taunts that would play specifically near certain opponents. We have the classic rivalries of Nasus and Renekton, Graves and Twisted Fate, Miss Fortune and Gangplank, Zed and Shen, Rumble and Heimerdinger, Jayce and Viktor, Katarina and Garen...I'm pretty sure there are others I could list, but I've made my point.