Humans like to categorize everything, including themselves. As others have said, we like to feel like we belong but also like we’re distinct from other individuals or groups of people. Many people i know take pride in being “different” from others.
However, I do think that globalization is taking away a lot of the unique traits of many regions of the world. For example. I remember being sort of disappointed when I got to Ireland and the majority of music I heard in public spaces was American (though there was some British thrown in). The movies playing at the Omniplex are all American, and a majority of the books for sale in the secondhand stores are by American authors. Where’s the Irish art and pop culture?
On the other hand, while the internet may be a huge factor in globalization, I think it’s also a tool for creating or propagating individuality — helping individuals find music, for example, more suited to their particular tastes, instead of relying only on the radio to find new music. Regional bands can gain a substantial following in their area, even if they never achieve national or international fame. The indie music people are listening to in Michigan is not the same as the indie music they’re listening to in Florida. I’m sure this can be applied to other aspects of life and culture.
So perhaps in my mind, developing a regional identity can be a response to globalization. I don’t think we as humans WANT to be the same as everyone else. We want to connect with people but we want those connections to mean something. I think a “global community” is superficial at best and that, beyond a certain level, it’s hard to truly identify with people with whom you don’t share a real space.
Or maybe regionalism can be viewed as a different sort of evolution: groups of people adapt to their geographical environment, and to thrive in different environments requires different skills/traits but also different preferences. Not everyone wants to live in a big city, or in the mountains, or in a hot climate. And I think having geographical location in common is one of the first, easiest, and oldest ways for individuals to connect with one another.