User blog comment:Ranger94/Does Shanks want to be the pirate king ?/@comment-3345720-20150822232858

He probably just wants to chill and go on adventures. Even then, you need great power, because a lot of shit can get in your way even if you don't mean harm just by being a pirate (as we can see with Luffy).

Not sure why he doesn't just take BB out though. Maybe it'll become significant later in the plot.