Not able to use the name 'Kain.' Reason?

[Cain_Azrael]

When originally making my character Cain Azrael, I tried every variation of using Kain as a forename. The surname was my intended original. Anyway, I eventually gave up thinking that every combination that would result in me coming up with a name that didn't make sense was taken. I've looked up every Kain name I could find on the main website however & to my surprise the name without some sort of silly additional text (Kainn, Kain', Kain'd) doesn't exist. I can get not wanting people to copy your flagship characters, but then I noticed the hundreds of Strife, Highwind, Zell Dincht, & so forth named characters. I don't understand why this one name is the exception.

[Raist]

may be because it's the name of an NPC used for a quest:

http://xivdb.com/?quest/66508/This-O...for-the-Lovers

[Cain_Azrael]

So is Cid, yet there are plenty of characters named that without variation other than surname. It's strange.

[MogaMan]

I think Kain is just the developers' baby.