League's had them in the past. Star Guardian Ahri for that one event, Gangplank for the other event in the past. They've done alternate announcers before so the technology to do it is there.
I don't understand why they wouldn't want to do it; it'd be free money.
You know how many people would pay for a Yasuo voice announcer or Ahri? It'd be shitting out free money.
It just baffles me that I can't pay to hear Akali voice acting everything or whatnot, I dont get it.
Also dear Riot if you ever do actually do this, Nidalee/Yuumi voice announcer please.