why can't the president sit down with a group of able and intelligent advisers and produce an ffective program to address the problems facing the nation?
He can, he has, and he does.
However, there are no easy answer and certainly no uniform agreement on the best ways to solve the problems facing the country. What some would consider an effective program would seem to be wrong to others. It's like all decisions in life. You have to trade a benefit for some people for a disadvantage for other people. But who can decide which group of people will get the benefit?