Good Neighbor is great but doesnt have that hang out feel.
A few more hubs would have been nice. I guess you can make the argument that you can build your own cities with the Settlement system, but for those you don't want that there could have been a hub or two extra to flesh out the world abit.
Retaking Quincy for repopulating. I really expected something like that you know? Clearing that Location so Sturges and so can go back and then after Time coming more and more unique NPC's to that Place. More Quests and all that [censored]. Same with Concord. That Town is huge too and also like Quincy just lost potential. Or after clearing an Option for a new unique Settlement, but in both Towns. To expand the Economy of the Commonwealth. New Merchants, Stores, and whatever for new fun.
Cities. Not city's. It's not that hard.
And yes, I hate the fact that they dumped cities in favour of player settlements.
But would a city even make sense from a story point of view? Humanity is supposed to still be trying to get back on its feet. No one has the resources or organization to hold a city together, which is why Diamond City is the biggest city in those parts. It's the "Green Jewel" because it's the closest thing to civilization humanity has been able to come up with so far. This is why the Institute looks upon the surface as a lost cause. A large city would have the resources and organization to be another faction in the game.
Forgot to mention there is Bunker City as well, which you can make into quite a nice little city. You can add your own vendors to the existing ones.