For astronomy 3-D is key.
Astronomical images contain hardly any cues for 3-D perception, while in our daily environment there are up to ten cues that help our brain figure our what is closer or farther.
Of those ten cues, at most three apply to astronomical photographs, and most of the time there is none at all.
The classic 3-D cue for spatial perception that has been adopted for spatial visualization in astronomy outreach is motion parallax. Racing through the universe at super-lightspeed provides a general sense of spatial perception...but calm contemplation of the wonders of the universe is hardly possible.
We keep stereoscopic viewing alive
Stereoscopic viewing in cinemas and on television is dead ... again. For astronomy we must keep it alive. Stereoscopic 3-D viewing (stereopsis) is the best cue for depth perception in individual objects, Let´s face it, in interplanetary, interstellar and intergalactic space neighbors are rather far apart.
Therefore the most effective vehicle to deliver spatial perception of astronomical images is through true 3-D modelling and visualization using stereoscopic viewing.
Different technologies for stereopsis have been found to deliver the necessary two different viewpoints of an object to the two eyes. Some of these technologies are more complex and more expensive than others. All have there pros and cons.