Each element can have the same abilities and stay different.
Let's use the example of healing the player.
Entropy is about randomness, and...well, I saw a good idea for this one, a card that switches sides and applies antimatter every 3 turns, thus, healing you half the time (assuming the opponent didn't do more boosting than you).
Death is about death and toxic materials, so it gets a permanent that heals you 1 point for every 1 point of poison damage dealt to the enemy.
Fire is about power and destruction, so it gets a permanent that heals 1 HP every time the enemy takes more than 10 damage from one source.
Aether is about immortality and copying, so it gets a creature that heals 1 HP per identical copy per turn.
Air is a lot about damage, so for every creature that is damaged, they can heal one HP with a new permanent.
Earth is about strong defenses, so they can get a spell that causes burrowed creatures to heal 2 HP per turn, until they unburrow.
Time is about forcing the game to flow at your pace, so they get a creature that causes 1 HP gain per card drawn.
I believe that would allow every element to have some form of life gain.
Would you say that if these cards were added, all the elements would be the same with regards to healing? I certainly would not, and I would think it could lead to a lot of new interesting decks, as well.