LOI's are the legal equivalent of "almost pregnant." Letters of Intent emphatically state that. They state that they are not formal agreements, and then often proceed to set forth agreed terms of the proposed transaction. Given this paradox, if the deal goes sour, one party can argue [in court] that those agreed_upon points were, in fact, agreed upon _ or, in fact, a binding contract. And, in some cases, furthermore, that the party relied on the LOI and has monetary damages based on such reliance."
Why would you ever have to sign any type of agreement before you ever see the terms. When shopping for a car would you sign a letter stating that you will buy a car for ุꯠᇸ and hand them your money hoping that they give you a new BMW when they deliver to you a 1975 Pinto? No of course you would not.