Summoners have to do during dots:
Ruin
Fester
Rouse
Spur
Enkindle
Shadow Flare,
Poison Pot
Bane
Micromanagement of pet (aoe) or contagion, movement of the pet ..., HP of the pet, constantly pressing obey if you change target
I might be missing a few things, but Summoner has plenty to do
Summoner should not be a support class since that is the Bard's job. All that Summoner needs is a small buff in potency (Fester must hit a lot harder) and an MP fix. No offence, though, but since you apparently don't realise what SMN actually have to do, your idea of support should already be dismissed