Mega Man 2 was even novelized as part of Nintendo's "Worlds of Power" series. Watch as James Rolfe semi-dramatically reads through it.
I do NOT need to watch that as I already read it. I had it (more on that later)
For those of you who never read it it's basically "Mega Man goes into a world with a Robot Master.... Mega Man meets Robot Master... Robot Master says some cliche bad guy thing... mega Man give a cliche response... Mega Man kills robot master... repeat 7 more times. Oh... and read I, Robot because an amazing piece of work inspired me to sit on my key board and make a pile of crap."
I paid a quarter for it at Goodwill and didn't even find it worthy as a collectible. I threw it out.
If it's merchandise that someone thinks will sell, and will pay enough to license, and Disney sees no reason not to accept those dollars, then it'll get made. I doubt anyone thinks along the lines of "Does anyone really need these books/T-shirts/pez dispensers/plushies/etc?"
The difference is, all those other things are collectible. Even coloring books/activity books have a charm. Maybe the little Golden Books that are in retro-style... at least you get the good artwork with them. But I never really saw kids get into junior novelizations other than trying to pawn them off as book reports WITHOUT actually reading them. Some teachers actually let it slide.
Though, I will say, why basically pull the audience of a movie out by giving the entire plot and movie away? I know even the kid's picture books have a tendency to do that... but again, picture books leave a LOT out.