IMHO, Las Vegas, at 2,000 ft altitude in the winter, can get pretty windy and chilly. I don't think it would be a good choice.
I told Todd Veney after we won in 2012 that winning the Winternationals in Pomona means more to us than any other race or division championship, and before we won I would have traded all of them for a Pomona win. Todd told me his dad, Ken Veney, had said the same thing. The Winternationals was the first National Event I ever attended as a young high school kid, and I think that was the year Alan Reinhart was born.
Bottom line is, for many racers life begins and ends each year in Pomona. Moving the events would be like moving Indy to Charlotte, and still calling it Indy.