Additionally, what's actually unfair is that you proceed with this spying without the consent of the user. Being upfront about it is not obtaining consent: it's just informing the user you're about to violate their (lack of) consent.
You must obtain consent from the user first, before transmitting their information. Otherwise, your software is spyware. (Disclosing that you're going to spy on the user doesn't make you not-spyware.)
> we use the data we gather in order to make smarter product decisions.
Yes, you transmit the private data of the user for the express purpose of enriching yourself.
Opt-out is unethical: you must obtain opt-in consent first. The data you are transmitting does not belong to you.