Because they should probably make room for someone more creative and/or talented. I seriously hope this person isn't designing all the classes because thats some of the most copy paste gameplay I've ever seen. If you watch the most recent streams, Pantheon rogues are watered down WoW rogues. They have the fast yellow energy bar, the ranged blind CC and a bunch of typical generic dps buttons that will likely turn into a mindless rotation.
This is a troubling lack of innovation with a game trying to avoid the themepark branding. Yes it's prealpha but that's the direction rogue has been going since their first stream and this is the best time for feedback. Designing a class with that many similarities to WoW shows a serious lack of understanding for the direction of the project or that person just doesn't care nearly enough.