Is there a benefit to representing a SID/STAR in 3D?
I have flown aircraft with Augmented Enhanced Reality built into their PFDs. They represent a desired flight path on the PFD with a rectangle whose unit of measure is dependent on the phase of flight. For example purposes, you would see a box on the PFD roughly 200 feet high by half a mile wide with 1 to 5 miles between each box in the enroute phase of flight. Your goal is to fly through each box. There is a dot or crosshair target on the screen to represent your actual current flight path based on trend vectors and statistics like airspeed, ground track, vertical speed, and rate of turn. Keeping the target centered in the boxes will keep you on your flight plan entered into the system. I have seen this system in Garmin and Dynon equipped aircraft.

Flight Directors and autopilots with Flight Directors can give you visual cues for pitch and bank corrections based on your programmed flight plan and actual flight vectors. 

Also, apps such as Foreflight will graph out your entire flight plan including instrument procedures in virtual reality. It will then allow you to virtually fly the plan in 3D for preflight planning. 

I don’t find this last resource useful in actual flight. Any other tablet based 3D representation would be just as bad. A simple piece of paper would be preferable in actual IFR flight. Any technology that would increase pilot workload any further than it already is in IMC would be dangerous. More than a couple of seconds to look at the information you need clearly displayed would be too long. The current charts facilitate rapid information retrieval by using standardized formats for every chart. There is no need to fiddle with gadgets unnecessarily. 

One way this can be very useful is for at home training. Get a few pictures as large as possible taped under your tv or monitor. Have all of your charts, sectionals, and checklists applicable to a real, normal flight out and ready. Then, chairfly the entire flight from preflight planning to hangaring the aircraft in detail. Play the 3D virtual reality representation of the flight on your tv or monitor when it comes time for the flight phase.

By the way, your standard ILS or GPS approach in a linked standard six-pack already represents the information in 3D. You just have to be able to interpret it as such.