Spec only players are something I dont really get. Most players I know for years, who like their class, they like every spec to some degree. And if you like the class and are able to get the time/gear you need for multiple specs there is a valid question which spec to play when the performance delta is big enough.
Since I like the class, I usually consider much more practical aspects, like how easy is the spec to play in this current content and is the performance delta enough to justify my choice. The DPS difference and the skillcap/practicality for each spec matters a bit more for me unlike weapon or spellanimations from each spec.
Thats why enjoy most spec vs spec discussions, because I allready choose the "fun" class for me.