The problem is that the news was delivered via tweet and blog by Darren Herman - a marketing/ad guy. He's a VP responsible for diversifying revenue. The source

The problem is that the news was delivered via tweet and blog by Darren Herman - a marketing/ad guy. He's a VP responsible for diversifying revenue. The source and messaging indicate more "user-enhancing" programs are also on the way. If Mozilla did not intend for this to be ad related, they picked a horrible way to deliver the message IMO. Mozilla would also be fully aware that there would be concerns about this "ad-like" product but did not nip it in the bud with any clarifications - yet. The community is concerned for a very valid reason.