I am neithrer hysterical or a dog hater. In fact I would love my daughter to have the companionship of an appropriate dog when she is old enough.
You say a change in the law would do nothing, but the conversation I had with the local neighbourhood police support team paints a different picture. Currently only 3 breeds of dog are covered by the dangerous dogs act in England. The police / park rangers are powerless to do anything about dogs of other breeds unless an animal does something that could be said to be evidence of it being out of control.
I asked whether they couldn't politely just stop the owner and ask them to put their dog on a lead and was told the response would be eff off.
It was the first really warm sunny day of spring and the park was rammed with small children on scooters, learning to cycle / playing ball.
I would be FURIOUS if an unleashed rottie came running over to sniff my little girl or play with her. It's not appropriate. And were it to attack, I'm not strong enough to get it off before serious injury would be sustained.
The problem is the owners aren't responsible. If they were they wouldn't be keeping big dogs like this in inner city London in the first place.
Most people live in one or two bed flats with (if they're lucky) some outside space that might be large enough to 'swing a cat'. I wouldn't coop a big animal up like that.
By extending the law to cover some other large breeds, the police would at least have the authority to take preventive action in situations where it's obvious problems might occur.
My local park isn't big enough for a dog area. Maybe it could be regulated by time of day? i.e. all large dogs to be kept on a lead between 10AM and 5PM. That way the kids can play and so too can the dogs.