While devs are all focused on creating new archetypes, and some are cool, all end up playing in the same way other classes do, just because they have limited destiny options. At the end of the day, they are using the same mantles and epic strikes.
I believe that the most obvious lack is an artificer tree, that could also support rogue/dark hunters and other trappers. Better trap placement, new alchemy traps. An improved flame turret (working basically the same way stationary primal summons work) could cast homing magic missiles or cast admixtures.
The options are endless.