Some of our summoner spells just aren't used a lot, like clarity and cleanse. They're both good spells, but people prefer other things atm. Other spells like barrier and clairvoyance I don't see getting used much without some tweaking to make them more worthwhile. I don't know if you were here when we had Surge, but that was a really good one, I think they decided it was OP so they nerfed it and then removed it if I'm remembering correctly.
Considering how much bang you get for your buck with ignite (true damage, dot, grievous wounds, vision of target), exhaust (slow, attack speed slow, reduced damage), and heal (health back, teammate health back, brief but significant movement speed buff), I don't see why barrier couldn't get some buffs (say increased armour and magic resist for 4 seconds?), and clairvoyance really needs something unique over blue trinket (like maybe boosting allies movement speed towards the revealed location within 2500 range). What do you think?