I have a feeling the odds are you are not looking hard enough or being objective enough about your own sites. The only pages I lost with this last update were ones that were either low quality or lacked high quality signals. Not having spammy stuff and not doing link exhanges isn't enough to get pages to be indexed in Google right now. To paraphrase a quote from Seinfeld show, you also have to have signals of quality to show your site is index-worthy. :)
Losing pages is a learning experience and often provides valuable clues to what Google thinks is or isn't a good page. Analyze the pages you lost compared to the pages that remained and look for patterns in the data. With my sites it is very clear and very reasonable criteria from Google's perspective as to what they think it worthy of keeping in their index.