Plain & Simple
It's never going to improve until they institute a couple of practices widespread in the private sector:-
1) If you're in charge then you're responsible.
2) If it all goes pear-shaped then you're fired.
Institute those two rules (normal rules, in my working life) and perchance we'll see some projects actually being given rational & coherent thought/planning.
But it's Whitehall we're talking about so I won't hold my breath...