That has been discussed too, and I don't think it's true at all. He has gone through plenty of change and self improvement, entire chapters have been dedicated to improving his art and execution to recapture the essence of the original, but it's not in the focus because this isn't something straightforward like Bakuman.
All of these criticisms come from the fundamental misunderstanding of what it is, because it's not a mangaka's journey navigating the manga industry, but a time travelling character draman and study that touches on creative philosophies, that happens to use the manga industry as a setting.
Focusing more on those complains would take away from what it's trying to do and turn it into just another manga about mangakas.
And it's still baffling to me how people can't differentiate between portrayal and approval and why they suddenly want the MC to be the paragon of justice (i know, plagiarism, even under this circumstance, is worse than murder). Only cool and badass characters can pull that off? If he was there would be no story to begin with.
Not that I'm saying the manga is perfect, far from it, but these are absolutely not its problems and their approach is completely misguided and kinda childish.
What touches on creative philosophies? They barely do did, they could have touch it if the MC went to his sensei to improve his work and made WK his own, but he didn't, I can't see how or when he made that work his own, I only see him "working hard" but I don't see the process.We also didn't heard(or barely) other assistant points of views asides the female MC, which would made the setting more rich.
If you want to made a non-conventional MC great,I love them if you do it right, but he isn't a non-conventional. He is your typical Shonen Jump MC, but with your typical time travel setting that try to justify the plot with the "if you lose , she will die".
That's the problem, they made the setting about "I give this manga for the future to save the girl". Is not about a man who have a Jump from the future an use it, is about a man who have a Jump from the future and he need to "steal"(i don't believe it's plagiarize tho) because "the girl will die". I don't have the problem with the second , but in this case it didn't work.
It didn't put the MC in a rough situation,in which he isn't the paragon of justice, he put the MC in a situation which he became the "white knight" (heh) to save/evangelize the damsel from her shitty and autodestructive believes.Peak conventional shone MC