the just-grown up
anyone with username that came up when they're in early teenagers, e.g. :
dragonlord-eternal-flameburst -> brook89
hiroyuki-ninja-samurai -> KennyBrand87

the going professional
someone that realize that their alter-ego isn't funky enough to break the industry
killerArtisan -> ArtieMcMillanArt
CryingDevilMayCry -> D'ArtStudio

the follower
"if everybody change their username, then I'm changing mine too!"
soulnine -> soul9
ErrikVanDerWick -> EVWD

the level-up
"need cooler username but don't want to change the way I am (or couldn't think of anything else)"
dragonknightxxx -> dragonpaladinxxx
King-of-the-Hill -> Protector-of-the-Realm

the repented race bender
someone that develop their senses of nationalism or just not that into anime anymore
hiroyukisama-no-kimitaisen-chan -> CaptainSteveRogers
naruXsasu -> JennaARTfolio

the disappointed fans
die-hards that called themselves victims of franchise gone bad
GreenLantern78 -> ReynoldsMustDie
HanSoloRules -> HanShotFirst

anything else comes in mind?