Besides the obvious answer which is a large amount of characters in the series, I really think Konohamaru and Hanabi got snubbed so hard. Honestly, the Sarutobi clan in general always has the worst luck. Hiruzen died in Part 1, and Asuma dies at the beginning of Part 2, never even getting to meet his daughter. Konohamaru lost 2 of some of his closest family members in like 4 years; that sucks. I don't understand how Konohamaru didn't become a powerful ninja given his lineage and the fact that one of his teachers was the LITERAL MAIN CHARACTER, like how many more benefits could you get? The anime actually gave him some pretty good clout, he managed to fight off fully transformed Jugo in BASE, and he inherited his grandfather's staff, gaining a monkey summon of his own similar to Enma. Along with his summon, he could also use a power sealing jutsu that could even seal away spirits. Sadly, all this awesome stuff is anime only, and the manga only seems to just start giving him a more important role. Unless he gets way stronger, I don't see him becoming a Hokage any time soon.
In Hanabi's case, she was always being touted as this prodigious fighter who even at a young age could beat her older sister in a fight, and was trained to become the future heiress of the Hyuga clan. I guess this was completely forgotten by the time Boruto came around, because she hasn't appeared in the manga once, from what I know. In the anime, not only is she a full fledged Jonin, she has her own team as well. I don't understand why she was so hyped up in Part 1 just to have no relevance in Boruto whatsoever; if she's a prodigy or whatnot she should at least be stronger than Neji by now or something like that. It would also be cool to see her interact with Konohamaru, like she did in the anime.
