Because it makes absolutely no sense. It seems rather odd that an omnipotent being uses a process with takes a staggeringly long time and leaves useless and energy intensive design flaws.
'Guided evolution' is merely religion trying to conform with modern knowledge with out making a lick of sense.
Perhaps what is staggeringly long to you isn't quite so staggeringly long to an omnipotent being. Had you considered that? You also discuss useless, energy intensive design flaws. What specifically are you citing?