The essay starts out well, with Hayashida making the accurate argument that the format of American serial comics (24- to 32-page monthlies, full-color, good quality paper) has driven the artform into a niche; whereas the Japanese standard format (large anthologies printed on the worst paper possible) has allowed manga to prosper and acquire a critical mass of content that is being exploited throughout the world.
There are historical reasons for this. At one time American comics were lengthier, had multiple stories per issue, etc. But as price pressures hit, American publishers struggled to keep the price at 10¢, lowering the page count (and ramping up the ad space) to keep the price of comics at a perceived sweet spot that could be afforded by children. In doing so they priced themselves right out of the newsstand and into comics specialty shops.
However, later in the essay, Hayashida goes off into flat-out wrong territory.
There is another reason why American comics stick to super heroes, aside from the page limit. It is because it is convenient for publishers to keep copyrights to themselves. Comics dealing with super heroes aren’t drawn by one author only. Numerous comic artists and writers draw the characters. The end result of this is that publishers insist that the creators can hold no copyrights. This an obstacle to the development of American comics and prevents improvements in quality.
I'm sure that this will come as news to comics creators like Dave Sim, Wendy & Richard Pini, Kevin Eastman & Peter Laird, Jeff Smith, Terry Moore, Chip Ware, Alison Bechdel, Sergio Aragones, Kevin Huizenga, Colleen Doran, Frank Miller, Brian O'Malley, etc.!
The statement that "publishers insist that the creators can hold no copyrights" is demonstrably wrong, even for the big two.
Hayashida makes the common mistake that American Comics = Super-heroes. They're not. Outside of comic specialty shops, they're not even in the majority.
Oddly, it was the exact same historical market conditions that led to the slimming and ghetoization of American comics which also led to the small-press and self-publishing movement. This movement has led not only to greater creative control and ownership, but also to great creativity and experimentation. I would argue that the past 30 years has seen at least as much experimentation and creativity in North American comics as in Japanese Manga (though admittedly my knowledge of the underground and art-manga movements in Japan is spotty at best).
While we're at it, let us put to rest the argument that there is no creativity or quality in corporate-owned super-hero comics. Watchmen, The Dark Knight Returns, Morrison's Doom Patrol, Gaiman's Sandman; all American corporate-owned comics, and all quite successful on both a creative and commercial level. Sure they are the exception rather than the norm, but they do exist and we'll continue to see the occasional gem surface.
The Japanese, North American, and European comic markets all took different paths of development over the past forty years. With the advent of globalization we're now seeing that divergent paths starting to cross again; a situation that I think will be beneficial to the art of comics as a whole. But to claim that one market is inherently more creative than another is sheer folly.