Please make event/optional items obtainable on all characters after obtained?

Main reason I bring this up is because I recently made an alt character obviously way after most of the seasonal events, but I have them on my main character.

While I understand characters have to be at the event to get the items and I would if I could, that's not the case, and I really wish the characters I made who did not participate would be able to have the items also, and especially so with optional items. I would rather not buy another snowman outfit for each and every character if I already have it for one.

Also, from what i've seen, most items from the events and optional items are untradable anyways and this is done with veteran items, so why not?