Peter Peacock told the spring conference of the Headteachers' Association of Scotland, held in Cardrona on Tuesday, that the 1988 school boards legislation was "a fine example of legislative micro-management - the no choice approach".
"It's full of detailed requirements and restrictions," Mr Peacock said.
"Formal election procedures, restrictions on numbers of parents, what can be discussed by a school board and what cannot.
"It offers no real leeway for what parents in a school might want to discuss or how they want to work. We simply don't work like this anymore."
Mr Peacock stressed that the proposals were "about strengthening parental involvement and representation, not about managing schools".
He acknowledged criticism that the proposed legislation was "vague" but said it had to be flexible to reflect what parents wanted locally. The Scottish Executive would issue detailed guidance in due course, which was the right medium for advice and information on setting up and running a forum, not primary legislation.
Guidance would include the role of headteachers who would not be required to attend the forums, in contrast to their membership of school boards.
But, Mr Peacock commented, headteachers and anybody else parents wanted to invite should play an active part. "If that were not the case, we would all have cause to be concerned," he said.
The gibe about "moaning shops" from Caroline Vass, vice-president of the Scottish School Board Association, was sparked by claims that parents would simply be talking among themselves. But Mr Peacock doubted this would happen, even without the headteacher's presence. "I think more highly of parents and their motivation," he said.
The minister also indicated that the Bill would repeal the schedule of the school boards Act and modernise the way in which heads and deputes are appointed. At present board members help in the selection and, without giving details, Mr Peacock said parental involvement would be retained.