The issue with Cure Minor Wounds as an at-will spell isn't any kind of balance problem, it's a matter of style.
Along with Endure Elements; Create Food and Water; and Purify Food and Drink, you're basically trivialising survival. With unlimited healing, your players will rarely suffer any serious setback -- as long as you can win a fight, any damage you suffered will be completely gone before the next. Without unlimited healing, you might find things become more interesting.
Presumably there are many groups who'd prefer not to deal with such things. However, even then, it might be better if those groups dealt with survival and healing through magic items or something comparable (ToME-style inscriptions, maybe?), which would help to ensure that nobody has to deal with survival, instead of only resolving the issue for casters.