In a comment elsewhere, Marina of B&B sums it up thus:

I, too, am surprised at how much I’ve been enjoying Boruto. I never watched Naruto, never even wanted to since the length of the series intimidates me. Boruto is my chance to jump into the world, though I’m worried about how long it will eventually run.

This alone is a reason enough for Boruto to exist.

Also, I can sympathize with the point about the length. The orininal Naruto was the longest series I ever watched, as I lasted for 146 episodes. Never again.