Too very true. I usually over complicate my projects as well...and what every colleague, firm, and even business class taught me...a refined niche is more valuable than a swiss army knife.
There's a reason the saying "there's an app for that," exists, because it solves a purpose and fills a clear and concise niche. If I can't pitch the core idea in one statement, I've failed before I've started.
To clear a little confusion by what I mean on unrefined products, I can think of a prominent Swiss Army Knife...Google.
If I asked you to convey to me what is Google as if I didn't know, you'd probably say they're a search engine. While I don't mean to discredit all the products Google has, they themselves have been known to kill off their own products (Reader, Checkout, Buzz, Wave, ect) to refine a centralized purpose (ex. if you sign up for youtube, you now have a google plus).
This is the art of the niche, bringing multiple features to form one cohesive purpose.
I think this is a case where the integration of all the features and data is more than the sum of its parts. The difficult part is knowing what the essential features are, and providing something useful until all of the necessary features are there.
1) think of the idea
2) code it (notate any epiphanies along the way)
3) optimize the code
4) package and ship
Here is the entrepreneur's perspective.
After all, we are not dumb. We may love to work but most of us wouldn't just want to take so many initiatives if we didn't get the impression that we must to acheive goal x.
In this case, goal x is often more funding or traction. And as part of the funding process, you get feedback about the milestones you must hit to get your next round of funding. Moreover, you get shit load of very conflicting feedback, in some cases by the same VC just on a different day.
Entrepreneurs trying to attack from many different angles are basically hedging their bets due to a lack of clear signal from the market.
The solution to this problem is not as simple as the original post makes it appear.
VC: I want you to put all your wood behind one arrow.
Entrepreneur: Which arrow?
VC: ... I gotta go.
The number one reason is of course, you doing things which you don't like, are not good at and not enjoying what you are doing.