Board Thread:Boruto Discussions/@comment-26389992-20171226011920/@comment-1512913-20171231145138

Exactly that. The Kote is for common folk, not Jounin + level ninjas. In other words, the plot goes as follows: 'Naruto and Sasuke and now aware that Kinshiki and Momoshiki were not the end and another alien invasion of possibly far greater magnitude is bound to happen sooner or later.

The ninja tech is developed for the purpose of defending the planet against the Otsutsuki.

For all we know, Momoshiki and Kinshiki weren't nowhere near the worst the Otsutsuki have to offer and far more powerful individuals might attack, closer in power to Kaguya or even exceeding hers. They are leaving nothing to chance.

If you learned that there is an alien civilization out there that goes from world to world and leave destruction in their wake and already experienced it first hand (Kaguya, Momoshiki and Kinshiki and to an extent Toneri, although not a 'true' Otsutsuki) then you wouldn't want to just sit and wait for them to come.