SMN does not need Sustain back. It needs an Enhanced Rouse.

[Rawrz]

What about those doing solo content without rouse or bahamut? or just trying to solo stuff in general as an arcanist or low level summoner?

And even then, it's not like they are taking away something to add in sustain, so why does it mean so much for you for it not to come back?

I mean at this point, its coming back. Say hello to the Summoners in your roulettes using sustain every 10 seconds to heal 1/4th of their pets health because they can waste time casting sustain, rather than placing their pet outside of the cleave. Enhanced Rouse was just a way to keep your pets health up, by doing good SMN things, like casting rouse. They are also reducing the cost/cast time of Summon, so I guess your GCD benediction. xD They could have just allowed chocobos to heal pets in overworld content, but meh. Waste your GCDS. Oh well.