That's really interesting! This looks like it has real possibilities, though as with any new technology, there are some possible drawbacks to work through.

Multiple transmitters in the same area would probably interfere with one another at the receiver. It will be hard, might be impossible, to distinguish two simultaneous bitstreams. This is much less the case with RF.

A constantly ON, very bright LED would compete at the receiver for intelligibility, just as an IR command can't be received by an IR sensor that's being flooded with IR from a plasma or an LCD TV that's just been turned on.

If no competing signal is present, a single LED light bitstream, flowing downward in a room, could be sensed through a window, especially if it happens to light up a nearly sheer curtain a little bit. There WILL be devices made to pick up very low level bitstreams.