Agreed. The trailers for all three recent films showed far too much. By contrast, Spielberg knew exactly how to do trailers properly, by teasing without showing the best bits. Examples:

Original Jurassic Park trailer (cleverly avoids showing any of the best dinosaur bits).

Original Close Encounters of the Third Kind trailer (behind the scenes material that makes the film seem intensely intriguing, but no shots of the aliens, mothership finale, etc).

Original Raiders of the Lost Ark trailer (doesn't ruin the plot, features no shots of the Ark or bits of the finale).

Original E.T. The Extra-Terrestrial trailer (no flying bikes, no shots of E.T. save fingers.)