24/7 doorman means someone to sign for packages.
A community of people who presumably are in your socioeconomic class will be living with you. These are folks you can interact with and depending on your stage in life you may potentially do business with, befriend, start children’s play groups with, or even date/marry.
Big communities tend to have nice amenities that you’d only find in a country club all inclusive.
Maintenance of the high rise unit is often included in the fees or rent.
These communities tend to get better access to interconnect technologies like fiber.
There will tend to be more options for healthy foods, increased opportunities for walkable restaurants and other forms of entertainment as the population density of the area increases.
And more...
Basically, my preference 10/10 times would be to live in a high density tall building over a single family home in a neighborhood.