Yeah, I think you’re right about more magic as the curse is broken. Emma IS there to break the curse (although she doesn’t know it), and she brings the magic back. If the curse not only makes people forget, but also takes away magic, then she is bringing memories and magic by breaking the curse, right.
OR, the curse might JUST make them forget, and because they don’t remember who they are, they can’t use magic. In which case, they all have magic at their disposal, just don’t know it, and when people gradually begin to remember, they can use it.