You guys are likely right that a film version of the 1974 SW rough draft would have been a box office flop (even if it did wind up becoming a cult classic later on).
The real problem with this draft is the characterization, or lack thereof. For instance, Annikin Starkiller has too much of Conan the Barbarian and Toshiro Mifune in him to be anywhere near as likeable as the wide-eyed naivete of Mark Hamill is in the final film.
But also, the rough draft as written would surely have been quite expensive to produce. If the film flopped in general release it likely wouldn't have made its money back.
Combined with the earlier box-office failure of THX 1138, filming this draft might have killed Lucas's film career before it really ever took off.
But in that case we wouldn't have Raiders of the Lost Ark. So I think overall the actual state of affairs is a net win.