If I buy a “programmable” irrigation controller, especially one that many people find confusing and request help on, and if new features can and are added over the years, I for one certainly appreciate an email now and then. Personally, when I register something, I ASSUME I will get emails about it. I appreciate if they have an Unsubscribe button, and then actually unsubscribe me (most don’t). And it takes only a click to make an email as spam and never see it again. Wish I could do that with spam phone calls!
I think the OP is extraordinarily upset by something that is pretty much standard in the industry and takes only a moment to eliminate if not desired. I, at least, have much bigger fish to fry on my complaint list.