Because they are still cool, after all these years. Even the dangers of over-exposure haven't removed that aspect of the lads. Hanging around in not much more than school uniforms with early guitars. Lennon at the fete. Leather jackets in Hamburg. Even those potentially ridiculous haircuts and suits at the heights of Beatlemania. Individual expression in the Pepper years and 'normal gear' worn with flair in the break-up sessions. How did they do it? Because they just were cool: trend-setting, innovating, devil-may care approach. And most importantly genuinely wanting to lead rather than follow, not selling out for their art. Not a constructed band: doing it because it was there, because it was in them, because they were passionate.
That's another reason we love The Beatles.
Reason 1: Story-tellers
Reason 2: Sgt. Pepper
Reason 3: Eternally optimistic