Because its wierd, and Honda likes to do it that way, until people catch up. They did it with a 2 stroke triple in 83 until the world caught up and then they went to 4's...widely thought that their R&D pointed that way long before. So they'll start with a big money 5, wait for the world, change to the optimum config R&D point at, wash rinse repeat.
It sux to see the 2S bikes go like this tho. 2S bike were always around, finally came on the scene in an evolutionary way, competing against 4S bikes of the same displacement, until they ultimately ruled. To kill them off with a capacity subsidy to their 4 stroke 20 year-gone loser cousins is a widdly ass way to do it, worthy of Harley and their endless rule fiddling conquest of the dirt track scene. I say they ought to let them do anything with 500 cc's, and build that turbo 4S, rotary (yikes!) or insane turbine idea on the shelf somewhere, wait for the world to catch up, etc.
The H.Y.S.K. (think: Borg) are buying a change, and that's just how it ends for 2S machines. But it sucked to see a lot of stuff other stuff go, like GT Prototypes or turbo F1 cars, and even after all this awfulness, gee whaddayknow, life does go on. Killing off the 2's takes with it a innocent/inconvenient bystander, that being the whole idea of the 500 cc benchmark as a premier class. Turning it into a support class is not a noble death, but a gladiator style mismatch, a spectacle.
And do you know what? It will catch on big time, even tho you know its not fair, because everyone still likes to see a good ass kicking now and again. Its like punching your little brother. You shouldn't do it, its not fair, but its still fun.