@aral I don't agree.
1. There are lots of things where there is benefit in aggregate usage statistics etc. where there's no reason a user would go looking to turn it on because it doesn't affect immediate product function, but which will make the product better over time when designers can see how and what gets used.
2. In the 'advertising' cases which are what tend to make people angry, the opt out is functionally the price of the product. Which makes the statement "if you're making something that wouldn't exist if nobody was willing to pay for it, maybe the thing you're making shouldn't exist". By which logic we would have none of the modern commercial internet. The world is better for things like Google existing than not.