Honestly, I think the problem with SMN boils down to the fact that we are the main damage dealers and the summon itself is a tag along, which is not something that many people want in a Summoner.
In most other FF games, FFXI included; the GF/Aion/Primal is the power (DPS/Support) behind the ability to actually summon. In XIV we give the mobs a terrible flu and then we blow them up with Akh Morn while the Egi chips away and is otherwise forgettable other then a few minor cooldowns (simplified).