Looking into my own stuff I believe it does come down to anchor over optimization. I vary my anchors big time and some of my sites got it. Lately I've been building links to domain.com or www. domain.com and I've started to see a little resurgence in the SERPs.
This update targets more than anchor variety, you need more links that use the domain or URL as the anchor. So if you're running a Payday loans site then just anchoring with a variety of payday loan related terms (good payday loan, fast payday loan, payday loan atlanta) isn't enough. You need more domain.com, more click here, more visit site type anchors.
Whats really shitty about all this is that even good sites do SEO. To capture good money terms you HAD to optimize and over-optimize anchor text just to compete with every one else, because that's what your competition was doing.