Releasing everything in one huge wave causes issues since we truly don't want to release a ton of items all at once to hit people's wallets with NRD after NRD after NRD (potentially). Then starts the wishes and cries of 'It's too much at once! My wallet/bank account can't take it. Make it stop.'
Releasing not enough of a certain type of product causes outcries as well.
As for the thought that nothing more than 1/6 scale figures are to be released from now on...well...off the top of my head I know of the following that are coming up for Pre-Order (soon/in the near-ish future)...
Red Sonja Premium Format Figure
Alien Big Chap Legendary Scale Bust
Apocalypse Premium Format Figure
Engineer Statue
Hellboy Premium Format Figure
Predator 2 Maquette
Predator 2 Mask Prop Replica
Kerrigan Statue
Yoda Life-Size Bust
Sinestro Premium Format Figure
Catwoman Legendary Scale Figure
Dr. Doom Legendary Scale Figure
Indiana Jones Legendary Scale Figure
Red Death Premium Format Figure
Queen of the Dead Premium Format Figure
Red Skull Premium Format Figure
Captain America Premium Format Figure
Striker Eureka Statue
Joker Life-Size Bust
Slattern Statue
Spider-Man Comiquette
Gwen Stacy Comiquette
And this isn't including the many projects either teased or not revealed at all yet that are still yet to come before the end of 2013 (that happen to be non-sixth scale related as well).
Is there a plethora of more and more sixth scale offerings? Yes, of course, as there are collectors out there that do enjoy collecting in that scale but there is no abandonment of Premium Format Figures, Maquettes, Statues, Comiquettes, Prop Replicas, Legendary Scale Figures, Legendary Scale Busts, Life-Size Figures, etc.