I think they should be allowed to charge you, if you use another banks machine...... but only if they have a policy where there is always one of their own cash machines no more than a ten minute walk away - this is why people use other machines, because in a lot of areas you'll have one bank, and people don't want to go for a 15 minute drive so that they can withdraw some of their money.
I'd also like to see it so that the bank compenstates you when their cash machines either a) run out of money, or b) stop working, if they're going to start charging for getting money from other machines.
Somehow I don't think it will happen though