I really don't understand it. - Content was used to spread malware/illegal content - It was not profitable How are those two things something you find out after the fact? What was the reasoning for launching the product in the first place?
If you were being cynical (and to be honest I don't think this is exclusively what happened here), you could view it purely as a short term marketing campaign. It generated lots of positive reporting about Firefox, associating them with: launching a new product, encryption, freedom and ease of use. It also had an element of virality, in that a passionate Firefox user could use the service to send to someone who doesn…
I agree with your final paragraph.