My own interest comes from nostalgia mostly. Many old games looked better using a voxel engine than contemporary polygon based ones. Though, of course I later realized in fact there weren't any real voxel engines in the sense of what I wanted them to be. I think Voxlap really was the first time we saw one.

Why the appeal now? Voxels are a simpler model for describing the world and adding granular detail, at least at first sight. Ultimately you still have to model bending, physics, animation, free rotation, etc. which is AFAIK more complicated than for polygon based 3D data. Essentially a voxel object still needs to have a secondary parametric representation to describe things like elasticity or connectivity, etc. (not sure how it's done), though I assume the techniques are not too far off from skeletal animation etc. in traditional engines (which also use such a simpler representation overlayed on / inside the mesh.

But I think that leads to the second appeal: Trying to squeeze out a few more polygons per second or a specific little effect on the fundamental technique level in traditional 3D engines is pretty hard but only gives you so much in return. I can understand how something you can approach with a fresh set of eyes, with fewer established working solutions, is appealing in itself. There's (seemingly) more to discover, more to invent.