Wow I can't believe you actually tried to answer. Just to clarify I wasn't trying to say that its wrong to find breasts attractive just spheres.
Try to understand, because you really did miss the point of my original post. All of the things you've listed here:>*firmness, lack of sagging etc sign of youth/health>*sign of how well offspring will be fed>*quintessentially feminine>*sign of female vulnerability, need to be cared for/protected>*directly show physical/visible signs of arousal
These do not explain "why" titties are arousing, you've kinda just listed what you like about them.
To really drive the point home I could ask, Why are firm spheres arousing? Why is the ability to rear offspring well arousing?
It is impossible to prove why someone subjectively likes something.
(I can also see that you've try to say we should find them attractive for basic species survival reasons, which obviously not everyone is born with)