The rising attractiveness seems to be surprising. Live is very expensive in the metropolis. Rents are high and they are climbing. Restaurants and other services are expensive too, the streets are crowded and it is noisy day and night. There must be some advantages which overcompensate high costs and other disadvantages.
I believe the most important reason for New York`s rising popularity is the fact that the metropolis offers plenty of Jobs. The city clusters a lot of companies in branches like finance, law, health care, advertising, publishing, fashion, internet media (for instance Tumblr) and more. And there are many public administrations. The huge diversity and number of jobs makes it is much easier there to find an employer than in smaller cites; it is also relatively uncomplicated to switch to a new workplace if that is needed (layoff) or good for the career.
And there are more advantages. The metropolis is home to a lot of Universities and colleges (New York University, Columbia University, Fordham University, Pace University, Fashion Institute of Technology, The New School, New York fFilm Academy, Hunter College, Baruch College and more). Science and education are getting more important because the global economy is changing faster and faster demanding more knowledge and skills. New York´s immense education possibilities attract not just students & teachers, they also allure ambitious parents who want to foster the development of their offspring.
New York City also is getting more attractive because the ongoing gentrification is turning former ugly neighborhoods in classy areas. You can see that for example in Manhattan`s Lower East Side & Chinatown, but also in Brooklyn, Queens and in the Bronx. Part of the gentrification are the sinking criminality (less risk to get robbed on the streets) and an improving environment thanks to stricter environment laws and better technologies (less car exhausts, less industry, more service providers = clean industries).
People aren't just interested in jobs & education, of course, they want to enjoy their leisure time as well - and New York has almost endless leisure time facilities. There are plenty of nightclubs, cafes, bars, cinemas and other leisure places. Thousands of restaurants cater almost any taste. And every night some dozens of rock concerts and other performances will happen there. The high density of the city also makes it easier to host and to attend parties.
If you are hungry for culture, New York City is the place. Museums like MoMa, Guggenheim, Metropolitan Museum of Art, New Museum and other collections entertain and enrich their visitors. The Metropolitan Opera and dozens of theater stages satisfy your tastes for ambitious entertainment and mental enrichment.
There might another reason why people flock back to cities like New York: Gasoline costs today twice its price from the 90s. The high costs of commuting from suburban areas for jobs & leisure activities make it more feasible to live in a center and are compensating partly the high cost of living there.
Today you can see a lot of construction sites in New York creating room for more people to come. It looks like that the metropolis will continue its growth in the coming years gaining more jobs and leisure time facilities. Welcome to New York City.