I'm not sure if what you're saying isn't true, or if I'm just biased and not able to see Atlanta from an outsider's perspective.
I left because I wanted to live in a big city, not in suburbia. Atlanta has some of the plusses of a city, but they're relatively limited compared to LA, SF, NY, DC. It's more a collection of suburbs than a city.
If suburban life is what you want, Atlanta is fine for that. Honestly, most of Silicon Valley is suburbs, outside of SF itself. And they aren't as appealing as Atlanta suburbs, with many more trees and a lot more space. If that's what someone wants, Atlanta is a better choice than pretty much anywhere in California.
One of the best things about California, particularly in LA and the Bay Area, is that there are more people living their lives according to their own unique desires than anywhere else I've ever been. Having "odd" choices about your lifestyle or having crazy dreams and aspirations is the norm here, and that's something I want around me. It's a plus for me to be surrounded by that kind of thing. There's some of that in Atlanta, but it's more localized to certain areas. Here it's everywhere, just how things are.
But I do get your point about "odd" lifestyles. We're certainly getting weirder here, but I don't think it can yet compare to what you see in NYC or the Bay Area. Still, there's a lot to like here, and cost of living alone is a great argument for Atlanta.
Atlanta is by far the technology hub of the southeastern United States. It has no competition to the west until you reach Houston (and even that is mostly specific to the energy industry). It faces only mild competition from the Research Triangle region of North Carolina, and beyond that it's a technology DMZ all the way to Chicago or the northeast.
It's home to Georgia Tech, perennially one of the top 5 engineering schools in the nation, and pumps out thousands of new programmers per year in addition to the thousands who migrate here. It has a highly diverse business base, not tied to any one predominant industry, and its Buckhead and Midtown districts have one of the most thriving startup scenes that you'll find outside of SV or NY.
Of course, if a Georgia Tech grad is in the uppermost percentiles, then odds are he or she would be enticed by Google, or a west coast startup. I'm certainly not saying that Atlanta is in the same league as San Francisco, or even New York (at least not its finance/quant opportunities). But my earlier point was that these environments are extreme outliers, and virtually no other city is comparable to that either.