A % chance to freeze and a 1 time healing that is dependent on the creature hp if you use it on it are absolutely crap compared to 1 extra damage.
Most creatures won't have the hp to make the healing worth it--what, are we supposed to only use gravity creatures now to make it worth it?
Along with the chance to freeze, why have a chance when you have a separate permanent, spell, and creature that can freeze, much more efficiently than the bolt.
10 quanta compared to 20 quanta to kill a 5/6hp creature is huge, and the 4 health you get from a 10 bolt and a what, 25% chance to freeze is positively worthless compared to the creature being dead.
Seeing this, fire bolt is obviously better than both these bolts in dealing with creatures.
With the current quanta cap of 75, you can kill a person with 5 fire bolts I believe, let alone needing 6. With the current quanta cap, drain and ice bolt cannot kill on their own. Drain bolt would heal you, but a 3 quanta heal card will heal more than it with full quanta, a stiletto will heal it in 4 turns without an enemy shield, etc. A one time heal of 16 max is useless in the long run which is what you would most likely be doing with 75 quanta. Ice bolt, with more quanta, has the ability to free the enemy weapon. Now depending on the situation, this could be entirely useless (an unupped arsenic vs a tit shield) or could win you the game (freezing an oe vs adrenacrawlers).
Seeing this, fire bolt is better than both these bolts in dealing with the player directly, with ice bolt being better than drain life, but only because of the ability to kill without any other cards.
The amount healed by drain bolt is not enough on creatures, nor on the player. The freeze from ice bolt is not good enough against creatures, and is situational against the player.
Now, 5 bolts for fire to kill a person over 6 isn't that much. All it means is that you can use one on creatures. Now, if all bolts had the same ability of killing a player without outside help, it would help even the playing field by making firebolt only really superior in dealing with creatures.
tl;dr: make the quanta high enough so that all bolts can kill a player without additional help