Why is value preposition is important ?

Based on Wikipedia, value proposition is a promise of value to be delivered and a belief from the customer that value will be experienced. A value proposition can apply to an entire organization, or parts thereof, or customer accounts, or products or services.

And so why is value preposition is important ? 

- By having this value preposition, we can reduce the marketing and sales cost, because the products itself already have their own value. 

- They can also stop the slowdown of the sales.

- Have the identity of their own, so it prevents from being the same as everyone else's

That is some of the reasons why value preposition is important, based on my knowledge.