Because that is how it is in all card games? Deck out should NOT be removed, that would be stupid.
Removing deck-out would completely remove the effectiveness of some decks, and while I, too, have been frustrated to no end whenever I deck out with the opponent at one health, I think a change that big is uncalled for.
You can always drop the opponents damage to 0 before you deckout too
example cards:PharaohFirefly QueenNymph Queen All these cards can create more cards.