Hikaro and Akira are both top class japanese pros at the end (skill, not dan-level). Akira of course, and hikaru, too (he nearly won the game against his sensei, wins against 5 or 6 dans).
And the whole story is about those 2 aproaching the hand of god, suggesting that they dont get a midlife-crises at 18 and give up go
So two more years of their current growth, and they would play in all tournment legues. Akira would have already at least one title, maybe hikaru too if he is lucky/has a opponend he's good against in the finale.
They would blast away all other Pros in japan, and then the real problem begins: Korea and China. A sad fact is that japanese go players SUCK. compared to korea. in real life.
And the author of the story had lots of support from asian go pros in the creation of the manga. If he had those two japanese pros kick koreas asses, his connections in korea wouldnt like it. If he tries to show the difference in skill, it would negate all the matches against the japanese pros.
The best solution would have been to end the manga like the last episode of the anime. A long 30-40 page chapter with teasers of the future of the characters, after the hikaru/akira match.