Take your new great idea. It is big. It is simple. It is just so damn beautiful it is going to explode overnight. So why hasn't anyone thought of it first?
Is it because everyone else is zigging and you are zagging? Is it because everyone else missed the boat? Is it that you are just that brilliant and futuristic-ally intuitive?
Or is it because someone thought of it before, tried to make it happen, and then got put out of business because they didn't see the glaring logistical problems, in-congruent target audience habits, or legal pitfalls of such a business?
The devil is in the details. When the honeymoon of brainstorming is over, take a long hard look (called due-diligence if you're an academic or like business-speak) at the details of who, what, where, how and why you are going to make this business work. Who knows? Maybe you'll solve the problems of everyone who came before you simply because you took the time to notice their very existence?