looking more at L-4 it seems like the natural high ground, allowing the occupant to drop rocks (or payloads) toward any terrestrial location with the least addition of energy. if (as harry stine suggests) we use perishable cutting tools (sawblades and machinist tools etc) as an industry to recoup the financial expenditure required to explore and develop our local gravity well, L-4 will probably be the departure point for shipping down to the planet.