Here's what bothers me about this situation. On their own, decisions about redirecting Firefox's monetized search referral system, or rhythmbox's monetized amazon referral system, or Banshee's, are individually somewhat understandable. But taken as a whole, this paints a really worrying picture.
Canonical are not the only game in town, and they do practically no application development. They're a platform business. But by turning off these features within applications, they're essentially saying "your business model will not be supported via our platform" to those developers that have software features which generate revenue.
The free software world is already desperately low on commercially sustainable free software applications. The ones which have proven to be sustainable - the likes of Firefox (whose revenue stream Canonical also impinge on) for example - essentially make their money via Windows users.
Canonical are free to set the monetary value of their platform at $0. That's their commitment, no one forced them to do that. But it's exceptionally sad to see them basically depressing the wider free software market by turning off features like these, and preventing developers earning revenue from software features.