Reading this it looks like some people blame old gay men attracted to bodybuilders for the shrinking of the posing suit. I don't think they have the power to force such trend so universally across the globe.
The shrinking of these little pieces of clothes is simply because bodybuilders have always wanted to show more of themselves. Isn't it that every bodybuilding competition has this advice or rule regarding the size of the posing suit and how much they can show in that area of the human body? The people who came up with such rule acknowledge there is tendency among bodybuilders to show more than "needed".
We are living in more sexually liberated times and the rule seems pretty much ignored to some extent... except in the Middle East I guess...