Can someone give me an in-depth explanation why Summoner is arguably the worst DPS?

[ViviAnimus]

Might as well drop it now then cause I very much doubt any info.

I am just hoping the earlier citation is true (about SMN being looked at and changing things pre 3.0) so it would make sense.

[Orrias]

I am just hoping the earlier citation is true (about SMN being looked at and changing things pre 3.0) so it would make sense.

I'm sure the job balance will be greatly adjusted when Heavensward is released, but do you have any jobs that you plan to adjust during the patch 2.5 series?

Y: In particular, I think we need to consider Summoner, but we're still working on the adjustments. Originally, we were planning to add new actions to Summoner with Heavensward to adjust MP consumption. However, since 3.0 is still a ways off, we're thinking about other careful adjustments. As we release each piece of content we see which jobs are too strong or not strong enough. We're also focusing on carefully adjusting things for 3.0, so we'd like to make adjustments as soon as possible, but please wait for a bit longer. (Source: http://dengekionline.com/elem/000/000/991/991969/)

I can't see them radically altering anything. I think modifications to the natural mp ticks during combat, the % of mana returned via Aetherflow/ Energy Drain, or perhaps even lowering some of the mp costs of the SMN's abilites will be as far as they may go, in terms of adjustments.