I assume SE's backflip with validity of the 1.0 Onion Helm codes (unused Onion Helm codes were initially redeemable upon ARR's launch) is an attempt to try and stop the recent incidence of unopened copies of 1.0 (both the Standard and Collector's Editions) going for enormous prices on online sites like eBay simply for the codes (although the registration codes for the game itself is still redeemable - as even though the 1.0 client itself is now obsolete and completely useless, the 1.0 codes are actually accepted as a code for ARR (and the 1.0 CE registration code actually also is accepted by the SE Account System as a ARR CE too, meaning you get the ARR CE bonus items automatically, even if the 1.0 CE item code no longer works.), not helped by SE encouraging retailers still with old unsold 1.0 client stock to be returned to them for disposal, meaning those copies which 'slipped through the cracks' so to speak would be even more valuable and sought after.

Because item codes included with Collector's Editions or merchandise are never made available through other means, I do not see SE ever bringing the 1.0 special items (Onion Helm, Garlond Goggles, Asuran Armlets, Sprint Shoes) back I'm sorry to say (as far as the Onion Helm went, this is the reason actually SE specifically added the Red Onion Helm and the Peregrine Onion Helm to 1.0 - so that those who did not get the Collector's Edition of 1.0 still could get an Onion Helm... of sorts. And this has continued into ARR as well.