Why is there a need for transport planning?

Transport Planning Notes

Why is there any need for transport planning? The simplistic answers:
"Everyone has or wants a car, so new roads must be built"
"If only public transport were better, I would use it"
"If freight were made to use rail, motorway congestion could be solved"
But, simplistic answers are:
not environmentally feasible, and/or
cost too much, and/or
not politically feasible, and/or
unpredictable in their consequences
If the simplistic answers are wrong, what are the right questions?
Possibilities:
"What sort of cities do we want to live in?"
"What could go wrong if we simply allow the trend towards sole reliance upon car travel to continue?"
"What sort of cities do we want to live in?"
Any consensus view would be too general to help in making plans
Someone, or some political agency, would have to play at god
Ideas as to what was desirable would change as ‘progress’ was made: Planned utopias often disappoint e.g.New Towns
"What could go wrong if ...