They definitely need to respect customer preferences, but I wonder how long their applications will last when everyone hides the revenue stream. There should be a trade-off between what the customer wants and what the business needs. In this case, it might be as simple as less obtrusive ads. They should take into consideration what task their customer is trying to complete and serve ads accordingly. Allowing rich media or animated ads when people are trying to read/write email is ridiculous from a customer-centric point of view.