Zettai Ryouiki/Headscratchers

Droy asks:

What does pigtails and tsundere has to do with anyway?

The point is that it adds in more "moe" traits, and therefore is more attractive. One person online mentioned that adding in kitty ears, glasses, and a maid uniform or Sailor Fuku would make the ultimate Zettai Ryouiki.
- The reason is that Zettai Ryouiki is more commonly seen on Tsundere characters along with the pigtails such as Rin Tohsaka of Fate/stay night. Tsundere characters alternate between hot headed and nice which is a trait that is commonly attributed to cats, which is why adding cat ears is considered moe. I have no idea about the rest though.
The idea of of this trope is to highlight innocent sexuality, and pigtails are representative of youth (see Girlish Pigtails), which highlights this further. Not sure about the tsundere aspects, but it may be because tsunderes are very childish, thus further highlighting that innocent, budding sexuality. But take my word with a grain of salt, I'm no anime fan.
It may be just a trend/meme started by Rin. Unless, of course, it appeared earlier than that.