Earlier quoted context omitted.
Those are completely valid appeals to emotion, because it is the emotional context of the reminder that makes it significant. If you don't understand why someone might feel bad after seeing that show up in their todo list, then you don't understand the problem. That said, as someone with pretty unhappy history with his father, I think what Google did here is fine. But really, not every emotional appeal is a fallacy.
When there is a perfectly good objective argument to be made (in this case, that undeletable reminders is a bad user experience), I do think an appeal to emotion is ineffective if not fallacious. In this case, the particular emotional appeal seems either insincere or unreasonable. Are people who have bad or deceased fathers offended by the very notion of Father's Day and the marketing around it? I doubt it, but even…
The reason it's important to talk about the emotions is that the emotional calculations change when the space or message is a personal one as opposed to a public one. It's the difference between someone coming up to you on the bus and asking you if you've called your father and a poster on the side of the bus asking if you've called your father. When you put your message in someone's personal space, you don't get to just say "eh, it's probably only a small fraction" because you're specifically communicating with specific people.
It is important to understand the emotional components of software.