I understand where you're coming from (and I counteracted an apparent downvote of your comment), but I don't think you're entirely right. Mostly, maybe, but not entirely.
There is a value in having good people work in the same room. I think it's overvalued, but it's not zero.
And if companies want to hire a top engineer in the Bay Area, they're simply going to have to pay more than if they want to hire an engineer in Des Moines: Competition for good local employees is much higher, and higher competition for fewer resources means that the rate for those resources will go up.
If you're a senior developer in the Bay Area right now making less than $115k, you're not trying hard to get a raise. If you're in Des Moines making $115k, you're in the long tail; the 90th percentile is $108k. [1] The MEDIAN in San Francisco is $115k. [2]
And that doesn't even fully capture the state of the industry, because there are a few employers who go well beyond the median. Most senior engineers I know who are working at one of: Facebook, Google, Amazon, Microsoft, or Twitter, earn over $200k (total compensation, counting stock grants), and many earn closer to $500k.
Des Moines doesn't have major campuses of any of the above employers (correct me if I'm wrong), so the increased salary pressure from the high rolling Internet companies isn't affecting the local market.
Would love it if more big companies would hire remote workers; it would "spread the money" around the country more evenly, they could probably find developers for less, and it would reduce the amount of greenhouse gasses wasted on commuting.
But until they do, a significant fraction of the best developers will congregate in the Bay Area, where they can potentially pull in $500k/year instead of a pathetic $95k. Because good developers are worth that much in value to the company, and any good developer making less than $120k is being exploited.
Even in Des Moines.
[1] http://swz.salary.com/SalaryWizard/Software-Engineer-III-Sal...
[2] http://swz.salary.com/SalaryWizard/Software-Engineer-III-Sal...