That's really the gist of it all...
Hasbro is about making $ and also saving it as much as possible. They know they'll sell more units in an uber articulated, incredibly sculpted, has it all Jedi Luke... than say a Hoth Trooper...
Chances are no matter how much someone may whine that a builder lacks this and that they will still buy multiples regardless...
Hasbro knows that, and it's unfortunate for some, but that's how it is...
Also collection#1 by far sold more units through to most retailers. The retailers go w/ what they believe will be the most wanted... and fastest mover... Because like Hasbro they are out to make as much $ as they can.
I think one thing that was over sighted that I mentioned is in the long run some builders may sell more units than some main characters... though keep in mind many builders will continue to ship whereas a new main character is replaced by an even newer one.
You may have times where a certain builder will ship in an additional four (or more) cases along after it's initial release...
Since the split of collections into 1 & 2 happened more ordering of collection one by the big n' mortar retail side has gone on because again they will sell better to the casual and new collector than say a Bespin guard...