I largely agree with this. I will still worry about it until/if she wins. I think a message to appeal to both suburban voters and working class voters could be better communicated. Again, I think part of this is definitely the truncated timeline.
And the backup quarterback could probably do a better job than the starter.
It's so easy to say "the messaging could be better." Actually doing it is harder. Much harder. And sometimes Kamala isn't the best person to do the messaging. That's why the campaign has been bringing in so many celebrity surrogates -- ones that people actually care about and who aren't washed up. As Plouffe said, they have researched who effectively delivers which messages to which audiences.
But the game is so, so difficult now. You have 5 seconds or 15 seconds to make a pitch on the internet before your ad becomes skippable. You have to make sure you don't create a sound bite or a Dukakis-in-the-tank image for the other side. You have to make sure the message to one group doesn't offend the others. That's another asymmetry. Trump can be out there promising giveaways to minorities to attract minority votes, because the white people know he's on their side. Kamala can't do that. She promises modest efforts at helping black people and it's "identity politics, woke, she wants to screw white people" blah blah blah.
Bottom line: The Dems have access to the smartest people in the country. You probably weren't alive in 92 when Clinton did "A Man From Hope" at the DNC, but at the time, it was incredibly buzzy. It was made by two TV producers (I don't remember their names) who had a string of hit shows under their belt, and they gave Clinton a Hollywood treatment. It hadn't been done before.
Ever since, the Dems have leaned on the creative community. It didn't hurt that so many people in advertising and media were gay and thus naturally aligned with the Dem program. Dems also have access to the smartest data scientists, smart researchers, etc.
And yet, with all this talent, the messaging proves difficult. Some people say, "the Dems suck at messaging." My response is that the messaging is really hard. There's no way they have all this talent and are also as inept as people think.