TightSlot, I'm probably what you would class as "young folk" but I do agree with you!
With the locked door policy it's unlikely that pax will hear cc address flight deck but I think it is important to use titles in public to maintain some professionalism.
When I make PAs to the pax I also try to refrain from using the Captain's first name, ie " ...on behalf of Captain Smith...". We've discussed this in PF Briefings before as a way of increasing security on-board. Nobody can gain access to the flight deck without using the captain's first name.