One thing that occurs to me about Reforging: Was it ever stated that it would/would not affect or be usable on Trinkets? I think that it could be pretty useful then.

Also, the way i've looked at Reforging be useful / interesting, is more like the BoA items, in that they're useful for leveling, but not end-game. So maybe Reforging will be useful for Off Specs / Leveling / that sort of thing, and the rare occasion that it is useful for End Game, but not to the exorbitant extent that some of us have speculated.

Besides, with Blizzard's gung-ho stance on simplification, why would it be beneficial to further muddy the modification waters by adding a 3rd game-changing way to customize gear?

Yes. If I remember correctly, it was stated in the panel that Engineers would be able to reforge trinkets and guns/ranged weapons. (I don't remember if the statement was 'guns' or 'ranged weapons', but even though only guns are classically associated with engineering, I can't imagine that they'd allow you to reforge guns but not [cross]bows.)