There's no such thing as the Story Stork. I wish there was. How nice would it be to have complete stories just delivered to my laptop? Unfortunately, I have to actually use my brain. That's easier said than done most times. After all, I ain't all that smart. I'll get an idea, but making it into a fullly-formed thought and turning that thought into a fully-realized story worth sharing takes effort. It's a balance between the left brain and the right brain.
You rely on the right side of your brain to come up with the ideas, the characters, and all the little pieces of flair that appeal to the escapism stories give. But, you need the left side to temper all that fantasy. You need plausible story lines. Things need to be logical, no matter if it's a contemporary police thriller or a science fiction opus. Superman can fly, because he is from another planet, where the forces of gravity affect his body differently. Wonder Woman's Lasso of Truth was made by Hephaestus from Aphrodite's girdle. Gordon Gecko studied economics and took huge risks that paid off for him.We buy these facts because they're presented as logical extensions of creative expressions.
Too much right brain, your story will fail because your readers simply will not buy it. You cannot expect to say your character has purple horns growing out of his head just because he does. You need to tell them that it's a common trait of his species, which was descended from aliens that crash landed 500 years ago and managed to cross breed with humans, which gives him a humanoid appearance.
Too much left brain, and you've written a manual, not a story. Six hundred pages detailing the shell scripts and compile switches the plucky computer hacker used to infiltrate the evil corporate empire's databases to expose their corruption with turn off all but the most die-hard of nerds. (10 PRINT "I ROCK AT BASIC" ; 20 GOTO 10 ; RUN)
You need to balance both worlds to be an effective story teller. I would say it's almost more important than grammar and spelling. After all, those can be corrected. Plot holes can get filled with a little work. But poorly-devised characters and situations, requiring wall-to-wall suspension of belief, or providing a dissertation or sermon is just insulting to the reader, and a sure-fire way to make sure your book will wallow in obscurity or ridicule.
Just my 1/50th of a dollar.