The statement just said that Halflings could be chubby, it didn't say that all of them were.
And like the idea of subraces of the different races, I can't see why a bunch of people hated the idea. Yes I know there were a ridiculous amount of Elf subraces, something like 10 or more back in 2e, but I never felt it was a problem. There certainly was nothing wrong with there being with Hairfoot, Stout, Tallfellow Halfings, along with Kender, those arctic Halflings and Athasian Halflings all existing back in the 2e Gnome and Halfling book.