"Aidan" is a traditional and legitimate Christian name for boys. I'm guessing "Aiden" and "Aden" are just misspellings done by people who aren't even aware of the saint's name. Then there's "Kaden," which is just adding a meaningless "k" sound to the front.
Names should be meaningful (e.g., an apostle, a saint, an honored ancestor or baptismal sponsor), not just a collection of sounds.
The fact that almost every Korean I know is named "Kim." What? They couldn't figure out other names for Koreans? Anyway, it is VERY CONFUSING. I figure that 3/4 of the Seoul telephone directory is nothing but "Kim" listings.