Bikini (Swim Suit) vs. Bikini (Bra and Panty)?

Bikini (Swim Suit) vs. Bikini (bra and Panty)? What's the issue?

It is an interesting observation where it is OK for people to see and appreciate a woman who is wearing a bikini swimsuit, but is somehow uncomfortable and inappropriate to see a woman in her bra and panties. In this day and age it can be really hard to tell which is being worn - undergarments or a swimsuit. Tanya and I were looking at a Vistoria's Secret catalog and we were not sure if we were looking at swimsuits or undergarments. That moment really makes me go 'Hmmmmm!'.

So what is the issue here people? If a woman undressed in front of you down to her bra and panties you would most likely be really uncomfortable, but if you found out that it she was wearing a swimsuit everything would be OK.

They cover the same areas. The only really difference is the material that they are made of. Are there certain materials that engage our prudish or propriety instincts? If this is the case, then why is this so? What do you think?

All of this is predicated on wearing a swimsuit and bra/panty that are not sexual in nature.