I believe a big part of why summoner feels this..."simplistic" is again due to the box Square Enix has coded themselves into as far as their game design. Where as in other final fantasy games summoner had more factors to worry about than just their dps that made being a summoner feel powerful and a very nice and versatile damage support (or even a 1vALL carpet-bombing dps depending on how ya built em).
Summoner had to deal with enemy status effects,
knowing what each of your summons did,
mana management and learning to save your MP for the right moment,
knowing what your enemy did because most likely you have a summon in your arsenals to counter that specific attack, but your needed to know what it is,
and not to mention Elemental weaknesses (one of the cornerstones of a Final fantasy game, and yet a simultaneous disappointment burried within this game.

all this on top of the fact that ff14 summoner has only 5 summons, 3-4 of which functionally do the same thing.
there is no CHOICE, like there is with other final fantasy games summoners.