Once a user is deactivated, they’ll have to reactivate their account via email. So this would still require an “effort” on their part.
When users from an old forum moved to our current forum, everything was via the invite email and no one complained. Most filled out their profiles except a few. The “hardest” part was getting them to do their profiles/bios. I think it would easier on you to just let your users go through the steps that are already set up - click on email link, set up their account… done. Just remind them they’ll probably have to change their username from the default that Discourse assigns (everything before the @ in their email address).