When I was a kid I started several novels. I managed to finish only one of them, and that by gluing together several different pieces of writing I had done separately. I didn't fail because I couldn't handle the level of writing or storytelling required, and I didn't fail for lack of creativity. I failed because I would start and write half of a novel without knowing why. Once I was halfway through and directionless, the realization would hit me that everything up to that point had been nothing more than a bunch of disconnected ideas that I thought would be cool.
At this point, traditional wisdom dictates that I draw a connection with the reader by asking the question, "What does this have to do with game design?"
What does this have to do with game design? I've seen and played my share of games that suffered from this same problem, lack of direction. And this isn't just about artistic integrity. Big budget games flop on a regular basis because they're imitating only the surface elements of other games without getting at what really makes those games successful. The original DOOM was a run away success, while RAGE pretty much clarified the fact that ID had lost not only its artistic integrity, but also its market foothold. (More on this here and here if you're willing to put up with a bit of "lewdness" for more discourse on DOOM vs RAGE)
All of this points to one concept. If you want a good or successful game, have some semblance of a direction. "Steal other peoples ideas and do them better" is still a direction, but "Oh, and this would be cool, so lets add it in with everything else for no reason" is not. I'm not saying that a game or book cannot be made up as you go along, but I am saying that the lack of a fundamental driving ideal will destroy a product of this nature.
If we put an artistic spin on this, one takeaway is that we shouldn't steal other people's ideas. We can learn from them, be influenced by them, and borrow mechanics used to express those ideas, but a work that is merely a regurgitation of other's works will always ring hollow. Another is that we need to have more than just ideas for surface elements. We need to understand if or what makes those surface elements have meaning or belong in our work.
From a business perspective, either do something novel or do it right. If you want to play the catch-up game by copying other successes instead of finding your own spot in the market, you need to understand what really made them successful. Mere attempt to resemble the surface elements of your competitors will be much less likely to turn a profit, not to mention the likely size of the profit in question.