Damage and aesthetic flavor is your answer.

The current design is BLM is a turret mage that focuses on Fire till low on MP and then Blizzard until back up to full and repeat. Enochian doesn't really change this and Summoner is a Necromancer type class that focuses on keeping DoT's up and micro managing their minion. And has a trance that enhances their magic by 10% and allows the use of a 400 AoE and decreases the MP cost of one spell. For a pitiful 15 seconds. Also gated by Aetherflow stacks. Which you plan out and is supported by Arc lore.

There is nothing wrong with these classes for this iteration other then Pets are under utilized and received no new skills in Heavensward.

Fact of the matter is Summoner gives you a more necromantic feel. I am not slandering your beloved Summoner in any way.

If I'm not allowed to have an opinion then say so and I shall move on to more interesting discussions.