I don't think we're looking at an aversion issue. Those of us with larger "beautiful equipment" actually feel pain when we have inadequate support.
When one is well-endowed the uniboob issue becomes a problem because then a great deal of sweat collects between the breasts. That sweaty pocket gets mighty uncomfortable. The uniboob can cause chafing, too. Yes, some of us have boobs big enough that they chafe each other.
A bra with support and separation can make athletic activities (even something as low impact as riding) as comfortable for us as for those with smaller breasts that don't need miracles of engineering wrapped 'round their ribcages.
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson