Bridges and Ports, I guess.
No, seriously, I don't know what they should do tbh. I'm sure people will hate it anyways. Proper beaches in vanille would probably help.
Regarding bridges, some of the vanilla Streets still have no proper bridge variants. That would be my minimum requirement. Footpath bridges and pedestrian street bridges would be great as well.
For ports, I'd like touristy ports mainly. And they should integrate well with the vanilla cargo and passenger ship piers.
For beaches, would you like it if they adapt the specialized industries tech they have?
So, you pick a beach entrance, set a boundary that includes a gradual transition from land to water, and that becomes a beach of variable size?
Maybe allow for some upgrades like additional entrances or facility upgrades like they have for buildings?
Idk, CS2 was cool but I bounced off it pretty fast. I just hope making bridges is easier, the way you have to mess around with elevation, road type etc. to maintain a waterway is very convoluted.