I guess this has never been properly fixed. I added a new user yesterday and assigned him a license and he never received the 'Welcome' email. There is still no way that I can find to resend that email.
Adobe, please stop acting like your products are perfect and will never fail. It would very helpful to provide remediation functionality like what is being asked for here. Between this sort of thing and the nightmares we're living with dealing with the new shared device license mess (along with their miserable "Are you still logged in?" popups), this is getting beyond ridiculous.
Please just provide what your paying customer are asking for. Just. Fix. It.