I could go all day on this one...and a lot of it points to the average human just isn't that smart...especially with their social and personal beliefs. But what
@Crazizniac said is right and more relevant.
I will say, we did it to ourselves. Men were the primary drivers of making women sex objects. So much so, that women adapted and picked up behaviors associated with it too. The entire world participated in this. That's why you have ultra conservative women who turn their heads to things that are explicitly wrong towards women. Well... if the world is convinced as a whole that making women these sex objects that you constantly chase is ok, then that means we love when they finally, "Holla atchya boiiii" we like it, find it entertaining, we feel special, and more importantly, we label it harmless.
Now the world is hyper-focused on how wrong all of this actually is...so the primary parts of that topic are going to see the brunt of the change...eventually the other behavior associated, will catch up. But it takes people thinking the way
@Crazizniac stated, and being consistent, for it to fully catch up.