In a large American city like Boston, Seattle, or even Chicago, I have access to a nice night life, good food, and plenty of nice museums. They're all great cities. When you consider them regionally.
In an internationally large city like NYC or Tokyo, I have all the access to local places that compete on the city and regional level, but with way more choices in that regard. But on top of that I have places that are competing internationally, as well as a large selection of the best other cities have to offer since there are so many people that move there from other places.
Its hard to get a sense for how amazingly convenient and awesome that is if you visit for a weekend or a week and haven't actually lived in a place like that.
Just going with food, maybe if you're ticking off a box that Seattle has a good ramen place you like somewhere in the city and NYC has one place you found that is as good. But theres a good chance there will be multiple places as good or better scattered all over the city in NYC vs the couple good places you like in Seattle.
Is there a new food trend somewhere else in the world? Its going to land pretty soon in Tokyo and if its more than just a flash trend you'll have a number of places competing that will be as good or even better soon enough. When I'm in Tokyo so long as I do a cursory look at the reviews, I know I'm going to get something good without having to go out my way, since the rents tend to put mediocre places out of business pretty fast unless they have a special circumstance surrounding them. If I am making a special trip for a restaurant in NYC, there's a really good chance I am getting something that can be considered some of the best in the world.