I did open E when I was a kid, to play adult's or more mature music, and slide. Had to play for older folks, the 20 - 21 year olds?
Decades later, I started with Drop D, popularized by EVH, to play wilder, younger stuff? I see it as a Baby Boomer's thing if you look at the time line. I don't think that the 80's music will ever go away.