Because a fight contested @ 164lbs is a super middleweight fight - a division where Ward, at the time, was THE champion. 1 + 1 = 2
Golovkin is not having all of his fights at 164lbs is he? he is fighting at 160lbs. He isn't holding a 168lbs title either.
He's also considerate enough to not waste people's time by asking for even money splits with fighters more popular than he is. 50/50 at 164 was a nice way of saying "you'd better counter us at least 60% to take that fight at 168. You buy the pounds you want". Instead, they got an offer to wait for a year to lock in to 50/50 at 168. Neither of those terms are compromising at all. That's a waste of time offer that nobody in their right mind would accept. Yet, a small contingent of vocal fans seems to have lapped it up with a spoon.
Same scenario imo. Your premise would hold water if Canelo had fought a ranked fighter at the full 160 lbs limit. Canelo has never officially weighed more than 155 lbs for any fight Canelo fought Cotto for two reasons..... 1. Its a big money fight. and 2. Cotto is in the same situation as Canelo is, neither feels they're full fledged middleweights, and both can make 154 lbs and still be strong in the ring. Now, if Canelo starts to defend the middleweight title against other fighters beside GGG at the full limit of 160 lbs and he's still demanding a fight with GGG be at 155 lbs, then the premise of Canelo being the ducker will most definitely hold water.
You're getting ahead of yourself calling him a ducker when he's yet to defend the title vs anyone. You were actually calling both Canelo and Cotto duckers before they even had fought. Lets see how things play out before we accuse anyone of anything.