If they did the SMN job would absolutely suck and be a DPS class with no DPS... and relegated to the scrap heap.
I think you need to be thinking in terms of something like that for SCHOLAR which is the support class side of Arcanist... Not for SMN.
Summoner is a DPS job in this game.
For the record though, there's a reason only ONE summon ever gets used while the others are little more than benchwarmers...
Garuda has Contagion... for +15 seconds of Bio/Miasma/Bio 2 on your DoT casts... (Bio 40 per tick, Miasma 35 per tick, Bio II 35 per tick... for 5 ticks (15 seconds)) ... total Potency 550 in a BANE Area of Effect or AoE. Plus Aerial Blast 250 potency AoE.
Ifrit has Flaming Crush every 30 seconds... ie 110 potency or 220 potency every 60 seconds... and Inferno (Enkindle) for 300 potency in a cone...
Garuda = BANE AoE 550 potency attack (60 sec recast) + 250 potency attack (Enkindle, 5y circle) = 800 potency in attacks.
Ifrit = 220 potency (60 seconds) + 300 potency (Enkindle, 5y cone) = 520 potency in attacks
Its a no brainer as to why Ifrit sits the bench. Titan is a tank... so not usable unless the actual Tank goes down or DCs.
ANY NEW PET a summoner gets...
Their last two abilities will need to dish out at least 800 potency in attacks in 60 seconds... or they will be sitting the bench too.
As to thinking SMN is a support class... errm no... you need to pick SCH for that. So I think that's the direction you need to go.
At this time, the SMN is an AoE class designed to take out large groups of mobs. Both with DoTs and DDs. With Pets, Spells, and DeathFlares.
EDIT: Think of it like this... the Black Mage is the DPS side while the White Mage is the Support class.... just as the Summoner is the DPS class and the Scholar is the Support class. That is how it plays out, so you're not going to give the BLM the types of abilities you give the WHM... any more than you give the SMN the abilities that belong square with the intents of the SCH.