It would be a very good idea, but it would require cooperation and a joint investment as part of an integrated implementation of scanners to read barcoded tickets.
As you say, the system works extremely well in countries like Germany, where it's not uncommon to see at least half the train presenting A4 sheets to staff performing inspections. Of course, that system is very well developed and accepted by the travelling public, to the extent that virtually any ticket (including the equivalent of rovers/rangers) can be printed at home.
Again, the ticket is secured against ID such as a railcard or ID card, I guess it helps here that many EU countries have compulsory ID cards which most people carry in their wallet or purse.
I have never quite understood the snippets of opposition to it in the UK (it was covered in a newspaper article somewhere), I would find it extremely useful and I know of many people who would benefit from it. Smart cards seem a long way off in the regions, where there aren't even TVMs at many stations - and if there is one, it may well only accept certain cards!
I am also skeptical that smart cards would prove beneficial to irregular travellers or those travelling on advance tickets. Additionally, a smart card is not necessarily tangible in the way that it cannot provide visible information to the staff or passenger without the intervention of a machine.