Breeds are a huge part of the problem and it's crazy to insist that they aren't. Too many large dogs around these days that have the potential to do serious damage. I am by large against these size dogs as for every one that is a 'teddy bear' there are plenty that aren't and that teddy bear of yours will have a limit they could reach and by size alone could kill somebody.
Of course smaller dogs can be aggressive, and any small dog breeds that have that temperament shouldn't be allowed to be household pets either. Smaller dogs are, by size alone, far less capable of causing severe damage of death (apart from the small but hench type!)
There are far too many Alsatians kept as family pets these days, I see them daily around here and I'm scared of walking past them and I'm definitely not alone in that. Big dogs are scary because of that potential they have to be dangerous and they should not be as common as they are, there should be strict rules on who can own them and what you need to do in order to do so.
I love dogs, I'm sure the people on here with huge dogs would mock my lovely little breed, however they are a companion breed, small, non intimidating and by natural temperament lovely to be around. Your right to own a big dog shouldn't trump other peoples rights to not feel scared or intimidated in public, when there are so many small friendly breeds available that do not carry the same risks.