Well...you're gonna get it! (just finished a bio of Spielberg..)

Spielberg is unrivaled when it comes to public speaking, and marketing oneself and one's films. Lucas has always been introverted (I mean, he even built a giant compound to cut himself off from the rest of the world...). Lucas also stopped making films, and then finally came back to SW years later. Spielberg has kept himself in the spotlight with unchallenging relatively decent (maybe, but The Terminal was unbelievably awful.) works since.

Of their individual sensibilities, Spielberg is much closer to the general consensus than Lucas. This explains his mass appeal to this day. Films like Jaws, CE3K, and ET have huge audiences simply due to their spirit. The Indy trilogy has the escapism of Lucas, but with the drive of Spielberg. This marriage of Jaws and Star Wars is what made these three films so appealing-they literally are the best of the two combined.

Regardless, I think Lucas and Spielberg both had lobotomies. Lucas made THX-1138. The robot made the prequels. Spielberg has not had a good film since Empire of the Sun and Last Crusade. I know this is probably taking it a little far-I admire these two, but really wish they would start making challenging works again. The entire point of making films is to grow as an artist..isn't it? When your best films are your first ones (DUEL!), what does that say?