It really could not get more simple than this, but all too many people insist on confusing themselves on this point by listening to bad advice peddled by people who supposedly have closed this deal or that deal or 50 deals on their word.
We find exactly the opposite to be true. If you were to go to an unknown area, would you want a map of the area? Well that is exactly what the LOI is: a map of the major deal points. In today's busy world it is important to be sure two parties are going down the same road and in the same direction before spending too much time working out all the details of a transaction.