The "micro-sites" you are talking about, and the long-tail SEO people are complaining about, are nothing new at all. It's been common for SEOs to build and rank sites like that for at least 5+ years.
The difference is Google made a big change to it's search algo back in April and in my opinion it was for the worse.
It actually ranked bigger sites (bigger than micro-sites but not necessarily the biggest ones) higher for less relevant long tail searches, presumably to weed out the micro-sites.
So the difference between now and 2 years ago is you are getting a less relevant result list, not that you are getting an SEOd micro-site.
I have a medium-sized website which relies mostly on long tail SE traffic,
Contrary to what many are posting here about this hurting sites that rely on long tail-- my traffic is above normal today. I'm not seeing a decline due to this search change.
I also would not see it in Google's interest to have less long tail searches, since those tend to earn it more money.