Think that has to do with the diversity of foreign talent in EPL teams. You've got tons of players from all over the world, which naturally draws the interest of, well, the world. It's not as marketable to watch an Athletic de Bilbao game where all them cunts are from one region in Spain, or any other spanish team where the majority of players are spaniards. Does this make the EPL a better league? Nope, as evidenced by how all English teams choked this round. It just makes it the most marketable league.
So why don't you (or they) watch more of the better leagues? If a league is better, surely that would lead to more viewership? All the people that you see on Twitter cumming over the Bundesliga, there's still a huge amount that only watch Bayern or Dortmund.