They suffer from the same thing all the martial classes do; lack of agency and lack of interesting play (largely a result of the former, but also because the basic loop of 'I attack' is kind of dull).
That they also suffer on numbers is just the cherry on top.

If WotC developed the skill system both inside and outside of combat then this may all change. I would probably argue that Rogues shouldn't be the only ones with good skills out of the martials though, in that case (Bard not being martial). Expertise is really where all skills should be (i.e., proficiency should be doubled when applied to skills the character is proficient in); I would probably have that baseline and give Rogues something interesting in its place (this being in the aforementioned developed skill system, so what that would be is either non-skill related as it isn't needed or would be related to the new system preferably in a non-numeric function).