Emission theory only seems crazy because you know all the evidence against it.
I think that applies to most beliefs that are called crazy, inferential distance works the other way too. Then again, some people simply fail to update no matter how much evidence they have.
Moreover, we know now that in fact some other sensory systems work very similarly to the emission theory of eyesight (e.g. bats using echolocation).
That's a good point, and I hadn't made this connection before, although I've done some reading on bats.
An insight I had a while ago:
When I'm out in the daylight, and I see a tree, what I actually see is not the tree itself. What I see is the sun reflected off the tree. Likewise with rocks, grass and birds: it's always the sun I'm seeing reflected off them. This is possible because the sun emits all visible colors (or rather, our eyes evolved to perceive almost all EM frequencies that almost all solid matter deflects). I'm not seeing the things. I'm seeing the light. We live surrounded by the sun.
Is this too obvious? Inconsequential? Redundant?