Cost/benefit analysis is what would determine priority at any IT shop. The main thing about paper tickets from a cost perspective is probably the hardware and the cardstock. The cost of keeping existing, working software in service is pretty close to zero unless there were a major system overhaul (which is needed) and the decision point there would be the incremental cost of retrofitting that functionality versus building functionality similar to what
@neroden proposed into a new system (which does not appear to be on the horizon). Maintenance cost of the specialized ticket printing hardware infrastructure is likely what would drive any decision to raise the priority of fixing it, absent a major system overhaul. That may not be a trivial case, since if everything were shifted to etickets, what printing that would still be needed, such as printing out forgotten copies of boarding passes, could be accomplished by generic printers, not specialized hardware (though it is not an uncommon item, airlines still use them).
As long as the cost of maintaining the ticket printing infrastructure is sufficiently low, this enhancement probably is a case of the "juice isn't worth the squeeze" as we used to say.