I very much agree with the points @burkay_ozturk brings up around this. I'm not sure there is a one size fits all solution, but we also migrated from Sakai and Blackboard many years ago and we would get complaints from students that their instructors were "spamming" them with too many emails from those systems.
The default settings in Canvas are that students would get an email notification about announcements and conversation messages, so I feel like any student who is not getting those right now actively made a choice that they do not want to receive them. The question then starts to become one of who should be allowed to override student preferences... For our institution, that would not be faculty. What we've heard from students (and faculty and staff) is that there is too much irrelevant communication in general, and that's why they just start ignoring everything, email, canvas, etc... So, I'm not sure how much an email override accomplishes in a positive way... One might say something like "well, I tell them to check email", which makes sense but that could also quickly be rephrased to tell students to check Canvas for their course announcements.
Overall, this was a somewhat "big" issue for our faculty for about the first year of our transition to Canvas, but now 10 years later, there really is very little chatter about it.
Personally, I prefer the current system of letting each user pick their own preferences to one where teachers (or admins) can override user preferences on their own. Like I said, I know it's not perfect, but at least for me it makes more sense.
-Chris