I agree, the general trend does seem to be towards less venomous species and has been for a while. Interestingly though, I think Chester's snake collection might actually be majority venomous as the only other species I recall them having are reticulated python, Boelen's python, red-tailed racer, and emerald tree boa.
Chester holds two species of emerald tree boa. Corallus caninus and C.batesi.
I think more zoos should keep venomous snakes My favourite is Russell's viper, which I have been told is a difficult species to keep.
About 3 miles from where I live is a breeding site for grass snakes. Every summer the local press is full of stories about the public reporting sightings of dangerous adders. One person even went as far as saying that it should be illegal to keep snakes as pets, in case they escaped just like the grass snakes had, the public really do need educating about reptiles.
Recently a man living near to me found a corn snake in his bin, why do zoochatters never get that sort of luck?
There is a private keeper near me who reportedly has the largest collection of venomous snake species in the country.