I realize that. I offered this approach as an alternative, as I
believe I can add the functionality to expand inline images in the
description portion, but i don't see a way to make the link portion
accept "aliases" for the file: protocol without major changes to link
handling.  Even then, it seems a bit like a hack.

[many use cases omitted]

Those are what I was thinking about for using other links as images.

Other than having to repeat yourself, wouldn't the
[[custom:file.ext][file:file.png]] syntax allow for most/all of the
use cases mentioned?

rick