I am actually in favor of this. Of all the places to cut costs this has to be one of the better ones. It is a minor hassle to print out the tags and it saves the cruise lines lots of bucks.
I run a camp and we have done this for registrations. We used to send all of our campers a packet of 8 documents that are required to be filled out to come to camp (thank the government for all of this paperwork!). We now just email the documents to them, unless of course they are in a situation were they can not print them out.
This saves us a HUGE amount of time and money!