The worst thing about rogues for me is the lack of animation compared to casters or even other melee classes.
It may be a non issue for gameplay but personally I think that looks are more important then function, since you have to keep looking at your character all the time.
What I think will make the rogue a much more fun class to play is to add animations like the anime Sword Art Online.
What happens is simple and not really complicated to implement (at least that is what I believe). Whenever a player does a special attack the weapon they use glows a bit till it hits. For this to work it has to be like SOA where the animation goes off when your just doing normal basic attacks.
I'm sure people will say stuff like ''it doesn't add dps so whats the point'', well my answer would be that for a person to have fun you have to notice that your attacking. The only reason why I know I'm attacking on my rogue is that energy is preventing me from spamming my special attack but otherwise their really isn't something that stands out, even the special attack of assassin rogues.
I'm sure their are some other nice animations but their are limitations to WoW, it has to be something not to demanding since WoW is a 8 year old game. Unless they can allow temporary scratches on mobs I think that making rogue attacks stand out more is the best buff you can give.