Do you think dogs should be allowed to be exercised in public parks without a leash?

In this post about dogs with no leashes being exercised in a public park a town is divided.   Dog owners think that the only way to properly exercise a dog is without a leash.  Other residents complain these dogs are out of control.

Do you think most responsible dog owners are being penalised for a few irresponsible owners allowing their dogs to run wild?

Or do you think it is only polite to keep a dog on a leash, or at least at heel, when mixing with the general public?