Uhoh - you propose a change down in the guts of the Everything engine :). While it would surely be the Right Thing, I guess that won't happen, because many things in the Everything engine are hardcoded to use [ and ] for evaluation. I also think that non-HTML-knowing people find it easier to put a link into square brackets instead of learning HTML syntax (though it would maybe be a good thing to force HTML syntax unto the people :)).

I think you will be welcome to submit patches to the engine that parse <LINK ...> tags in a special way, but I don't see that square-bracket-linking will go away soon ...