I think it has more to do with economy and DOTM than anything else. Hasbro had to raised prices and shrunk toys because they weren't expecting to do that well last year and the year before that. 2011 was probably compound by the fact that most of the DOTM movie character toys were like third or fourth versions of characters that a lot people already had. Remember how much trouble we had getting new toys? it was because retailers didn't want to buy them to sell to us. If you go back and look at the DOTM toys, they were really simple compared to their ROTF counterparts. Meanwhile a lot of the toys that didn't make it to the big screen were way better in quality.
As for the new voyagers, well no crappy mech tech weapons means more money to spend on the rest of the figure. In addition, if the beast hunters deluxes are any indication, they kept them on the small side because they might end up extensively retooled down the line. So to make sure they fit packages, and accommodate new weapons and stuff, they had to take a hit with the initial versions of them. I think bulkhead and ultra Magnus are good examples here. With the FOC ones they didn't plan on using the designs so far out, but there were two FOC Soundwaves in the first wave, and the same toy was retooled for Blaster. Meanwhile a lot of the Datadisc bots and cons are just retools/repaints of each other. I imagine there'll be a Blaster reprint soon, and Grimlock repaint or retool into Overkill or Trypticon.
Tl;dr: bad economy and DOTM meant bad sales, so they skipped on few things here and there. Also,Hasbro learned to get more milage out of a single design if they plan on retools early on.
