Maybe the animal cons weren't selling and combiner wars exceeded expectations and retailers said 'More like last year's product please!', as they do. The shift toward standard Decepticons is a shame anyway, while I don't think trainsnakes and tenacle monsters are doable at retail, I would still have liked a toy of Steeljaw that was actually good.
If retailers wanted "more like [CW]" I think they are going to be sorely disappointed by RID combiners. They're clearly going to be a smaller product with different emphases.
My gut feeling is that we're getting the '86 combiners again because that's what we always get because that's the 1984-1986 stuff The Core Fandom wants. Probably it's a little cynical, but hey. At least we're getting Galvatronus and Ultra Bee.
And yes, the G1 G1 G1-ification of RID has me saying "at least we're getting Bumblebee, Sideswipe, Strongarm and Grimlock again".