One important factor, probably overlooked, is that there are no pissed people in town centres any longer. Every Friday and Saturday night most urban hospitals are full of the walking wounded from a night's drinking. Add in all the drinking-related violence happening at home and you've got quite a busy A&E. I remember watching a documentary where a nurse said to camera, after another night of chaos "If there wasn't public drinking, none of this would be happening, and we'd manage quite well".
Take all the pubs and nightclubs out of the equation, all the drunken drivers etc., and then all the people too scared to go to hospital who are possibly dying at home instead - I suspect that's what's happening mostly to the numbers. I presume most street-gang related knife-crime is also down, on the grounds that most of the potential perpetrators are having to sit watching TV with their mums instead. Probably better for them - and everyone else. As long as they don't stab their mum.