The best explanation for why we love big breasts is purely sexual. We are one of numerous species who have evolved different attributes that have no purpose for anything other than the fact that they stimulate sexual appeal. Females and tits fall into that category. My personal ideas for why male's appeal to tits began in the first place and stimulating a positive feedback loop of increased size of tits and amount of attraction was for the purpose of gender identity. IOW, a cave man would more easily identify a cave woman due to her figure, and the most important reason for that identity was tits. This then meant that chicks with bigger tits got more sex and thus more babies, while dudes who like tits had more sex and made more babies. Feedback loop commence, and here we are today.

We tend to not dislike fake tits because senses don't care about knowledge, and senses are fuzzy. Senses are general and automatic.

Also, even though humans are finished evolving 'naturally' for the most part (due to the societal elimination of aspect of evolution like genetic drift, genetic flow, punctuated equilibrium, etc) if we did evolve it would be more towards liking fake tits especially since several decades or a century from now the large majority of sexual activity will be with 'fake' partners via virtual reality and/or artificial intelligence.

And so I don't clutter thread