Tell me I'm wrong about Needle Darts

My group and I made the switch from DnD to Pathfinder fairly recently and while I think we're doing our best to adapt to the new system there are still a couple of things we're still figuring out.

In our most recent session one of my players, a bard, cast the spell Needle Darts because she thought that on a hit it did full damage, or in her words max damage. I the DM, thinking that it was odd that cantrip either did nothing or max damage, checked the spell and saw that it called out that the spell did 3d4 piercing damage and told her that she would need to roll damage.

Seeing her face go from excited to crestfallen was really heartbreaking, especially since she was excited to just do 12 damage alongside the party's fighter who is regularly knocking out 50 to 60 damage (EDIT1: I was misremembering the amount of damage that my fighter was dealing, it's closer to 40 to 50 damage with vicious swing, Tengu Weapon Familiarity letting him treat a Falcata as a martial weapon and critting more regularly then everyone else and the Falcata's Fatal d12 trait.) per hit (EDIT2: I've just noticed another error of mine forgive me I should have said per turn rather than per hit) at level 2. I know that I'm probably right about how Needle Darts works, but if someone could tell me I'm wrong or give me advice to make combat a bit more fun for the rest of my group I'd really appreciate it.

EDIT3: Wow I got way more responses than I ever expected, thanks everyone for the tips and advice there's some really great stuff in here! We had another session last night and I tried to lean into the tips that everyone gave, and my table seemed to have more fun during the session. They're all looking forward to the next session and I'm looking forward to employing more of these tips!