[MENTION=6683613]TheCosmicKid[/MENTION] - given how warlocks cast, it's not surprising that they lack buffing. Note, that some of their buffing comes from Invocations - Sculptor of Flesh gives Polymorph for instance, but, yeah, they really aren't going to be rocking the buffing boat any time soon. Makes sense when you have so few slots per short rest. When you're only casting at most 4 spells per 2-3 encounters, it would be very surprising to see them being spent on buffs.
I'd argue that warlocks don't get the Potion spell simply because it's out of what warlocks do with their spells slots. Now, I could see an invocation for creating potions. That would be VERY cool. But, that's a different beast.
OTOH, I really don't get the issue with wizards having this spell. Niche protection is NOT a 5e thing. When clerics can cast fireball and haste, what's the problem with a wizard who can cast a minor heal? Seems to fit nicely with the whole "White Mage" thing people talk about.