It's never acceptable. It's essentially theft. If your disk is broken, return it for a new one. If you bought the game and lost it, too bad. If you lose your laptop, you cant just steal one, you have to replace it a proper way. It the same with games. Just because you owned a copy of the game does not entitle you to get other copies of it for life. If the game is no longer sold, then there is a good chance that it can be found somewhere on the internet from someone who is giving it out for free or at a minimal price. Seriously, this issue makes me mad.