With reference to your editorial (aj 14.5.98), you appear to be wanting to reconcile the need for less interference by planners with the need for knowledge of the skills which good planning offers. The editorial wants a formula.
You say, 'In the case of architects and engineers, what we seek in their creative combination is a formula where one plus one definitely makes more than two - and has a social purpose as well'. The formula is: architect + engineer + planner = 3.
What may well be wrong is the 'gifted amateur' system within which much planning operates. We have just agreed to have a Mayor of London with responsibility for strategic planning of the capital - so some structural change is about to happen. Let us hope that it at least results in a much greater emphasis on product than process - which is where the problem seems to lie: a concern about what the development should be and look like and how to achieve it in ways acceptable to both promoter and society rather than the time taken to decide it.