how would making it so it blocks 1 damage and does 1 damage to each enemy creature make it worse?
While it would be more powerful against many decks, it would be useless against some decks that it completely shuts down in its current state. For example, if we were to play a match, and you were using a RoL-Hope deck and I played this shield, you lose. If it had 1 damage reduction, your RoL's would live and you would not be shut down. Honestly, the card would work find if the upped blocked 1 more damage, but that would have to be balanced out by a cost raise, which is bad. Cheap, effective shields > expensive, effective shields.