Elvis was part of a much earlier generation than Michael or Madonna. That's why his music hasn't transcended as well. I'm sure most people are aware of his big songs though.
He still sells tons of records every year. He's one of the most influential artists of all time
It's like asking these 13-22 year old youngsters why they are not into the 60's music of the King of Rock n Roll. It's atrl and i've even read some people here don't even have songs on their iPod older than 2000s songs.
I do, TLC's "Red Light Special" still s**ts 'til this day!