I think it would be technically possible to expose Source Template fields to the Search and Replace dialog and to the Search dialog. But I think that doing so in a meaningful way would be extraordinarily difficult.
I don't do any SQL programming or editing, so I'll take your word for it. But difficult or not, I still really miss the power of those other fields that Search and Replace could access in the early RM versions. So I still wish for that capability to return.
But I'm not holding my breath, because I don't look that good in blue skin.