The LOI as it is now used is a misunderstood application of poorly informed brokers and traders. A more proper application based on established custom and practice in International trade, going back even to the old medieval "Law Merchant" (Lex Mercantilis) is: Buyer requests a quotation _ in modern usage this is an RFQ/Request For Quotation _ NOT an LOI. Seller may then reply with a Quote. Buyer confirms receipt of quoted prices, and requests an Offer.
To conclude, there's perhaps no more apt way to conclude this piece, than to quote this very fitting statement by contract law attorney, Ivan Hoffman, of California: "[Given that] the letter of intent is essentially a legally worthless document [but yet one that could potentially cause many serious legal problems for the signer]. It is not clear to me the reason any party would ever bother to create such a document and yet I have seen it used on many occasions."