Shock value. They HOPED that the implication that Naruto is dead at the beginning would lure readers in and maybe their curiosity would stay long enough to draw them, in because immediately after that They are starting from the beginning to build up to that very moment by rewinding things back to Boruto's childhood and thinking that would engage the audience enough for them to buy the manga. Too bad that on top of Naruto's name being completely ruined for NH, the Boruto manga is coasting along by boring the readers with unnecessary dialog and exposition and also ripping off anything that can be thought of. There is the ocassional decent fight scenes but nothing outstanding and it doesn't erase the dragging snail's pace to get to it. Not to mention it is stated time and again that Boruto, some way or another will get even stronger than his dad for no reason at all by being HANDED powers at an even worse level than Sasuke ever did.
Then there is the narrative problem. Now that Boruto's dad and Sasuke are "the stongest ninjas" on the planet, they are resorting to the cheap tactic of "worfing" the two of them against villans that are stronger than Kaguya, or they are explaining why the two of them are having such a poor showing when there are suppose to be none stronger than them on the protagonist's side. the fact that they are resorting to these moves to stretch out the story as long as possible only shows how ill planned the entire thing was after Naruto ended JUST to make money and how they actually have no idea on how continue the story. They are just doing it. For no real reason
Well it may have gotten readers interested then they wasted TEN MONTHS rehashing a movie, Five Months on a irrelevant prologue story with a richie rich character, and when they finally got to it...its just the SNS conflict and the akatsuki ripped off so blatant they barely try to cover it up. Then the rest of it is either fights that take 3 months to get through or expositions so obvious and blatant that even a utter moron would find it insulting.
They could have avoided that by having Bolt go on missions where you can't summon those two by blowing a whistle, or not having the first villains be stronger than the final boss of the sequel who was basically GOD at the time.