Peoples view of what a game is. People really only see the end product, the visual part of it being the most outstanding to them, apart from the audible part. I think this is because we are (mostly) a visual species, while our eyes "refresh rate" is not too good compared to other species (wave your hand in front of you) we still have good resolution and can recognize with our larger brain mass: body mass ratio more people, places, and things.
So I have noticed over the time I have been a member of this forum that many ambitious people looking to create a game come to Irrlicht mainly because it is a graphics engine, they see the demos and perceive it to be the same as an end product, when they are not, they are simply renderings, "pictures" not actual games.
Many would-be devs soon begin to find out the enormous effort that goes on behind scenes into making a game. Some are turned off by the realization and quit, while others don't. I think many people download Irrlicht or any other graphics render engine expecting it to handle data handling it does not.
Now, I began day dreaming about this other branch, one where our greatest sense is that of sound. We have very acute hearing and instead of having developed lush displays in 1080p he have engineered EXTREMELY accurate true, full surround 3d sound systems. Bats, dolphins and many dogs, who rely on sound, when it gets dark, or in the deep ocean to know their surroundings.
If that were the case with our species then I think many people would flock to an IrrKlang type library, since sound would be the highlighted part of the video game end product.
I hope I made my thoughts clear..
again, just thoughts.