Incisive, researched and robust as always but if I may +Mike Elgan
1- manipulating users mood is actually the core business of ad sponsored media (thats how you maximize impulsive behaviors in general and purchase intent in particular), specifically TV.
2- Apologizing is not a bad business practice. Apologizing a lot seems to me a good sign: they are pushing the boundaries.
Not sure what to blame here, unless you want to blame a broader systemic issue that goes far beyond Facebook: when its free, you are the product, (unless there is a broader consideration at stake)