I like bards, I really do, but when there's only 4 people they dno't fill any of the needed niche's very well on their own (they may do fine as the healer), they make great support of other classes.
In 5E, Bard are full caster. I would agree than in most rpg, support classes tend to shine with larger party. However, that's not what bard are in 5E.They can fulfill almost any roll (from healer to CCer, etc.) and be really good at it as long as you build them appropriately.