The problem is practical; do your users want the features or do they care about privacy? Let them make the choice, and don't hide it from them. That's the ethical behavior.
It's unethical to assume everyone values everything the same, including privacy. Some people don't care about it as much as you do, nor should they.
There's no ethical argument for depriving someone of food but people fast all the time. Further, the war crimes my gym trainer is guilty of know no bounds!
You can give up your "human rights" for convenience/pleasure as long as you can reassert them down the line.
Fasting and training are both conscious deliberate choices - how will you frame the loss of privacy in such a manner that it can be agreed to with the same degree of intention? Most people have no idea and don't understand - if you wanna go with the "opt in" solution, you're going to have to make a compelling argument that the people making the decisions are educated enough to make them.
Given a hospital patient who doesn’t value taking care of their health, should it be ok to administer X-rays without concern for radiation exposure? If the patient doesn’t care, is it ok then?
Given a person who doesn't like their nose, should it be okay to provide cosmetic surgery to that person, despite the risks any surgery comes with? If the patient doesn't care, is it ok then?
Given a person who wants to jump out of a plane, should it be okay to let them, even though it's a relatively high-risk activity? If the jumper doesn't care, is it ok then?
Given a person who wants to run for national public office, should it be okay for them to release their prior year tax returns, even though it's an exposure of their privacy? If the candidate doesn't care, is it ok then?
Turns out, this isn't an easy game to play, so stop trying to decide for others what they want for themselves. You don't know their situation.
The problem is practical; do your users want the features or do they care about privacy? Let them make the choice, and don't hide it from them. That's the ethical behavior.
It's unethical to assume everyone values everything the same, including privacy. Some people don't care about it as much as you do, nor should they.