It's minor, but with the addition of Bard, it's much more pronounced to me. I feel rather frustrated that we can't have more characters playing instruments. There are a few backgrounds that provide the ability for characters to have a proficiency in an instrument. Bards should naturally gain more proficiencies in instruments and such, but I'd LOVE to have some other characters able to pick up instruments along the way in the game and use them.

Examples of Backgrounds that provide instruments proficiency are:

Entertainer
Far Traveler
Outlander

There aren't that many, but it would be nice to have a few who allow you the option to create a non-bard musician. I mean, they can't use instruments to cast spells, but they can still perform. It would make finding instruments more meaningful, and I really don't like having to waste an ASI on learning instruments. That's such a waste.