That's more of a philosophical question than a technical one, and it may not be my primary role to answer it.
That said, I think you had the answer in your question. It's partly a matter of interest on the part of voters. There are some Canadian voters abroad who remain interested and want to vote in elections. Our job is to facilitate that and to ensure the integrity of the process.
However, it's not Elections Canada's job to engage people who are no longer in the country and sometimes haven't been for decades. Maybe the political parties will want to do that. Maybe there are other interests and other groups that want to engage them, but I don't think it's Elections Canada's job to engage people. I mean people in general, but especially those who left the country several years ago.