That said, I don't think it's a problem with the way low level content is being handled.
Shopshae, Toto-rak, caravan security, levequests, behests, level 25 ifrit battle, all of those are balanced towards light parties.

With only 4 players, an AoE cure is hardly needed. Sure, it would be handy, but not exacltly unbalanced. Specially since anyone can self heal with cure after killing 3 or 4 rats.

Not to mention Sacred Prism is level 34 (grants AoE to one healing spell) and is not class exclusive.