Image manipulation software can do a lot, but most of the time it is used over the top. All that technology causes most ads to look worse than those elegant compositions from the 1960s.
First of all there are the clear Photoshop disasters such as this nice composition below (via the PSD blog).
One step up, designers get the technical execution right, but the chosen concept just hurts the eye (via Ads of the World).
Finally, it possible to get it right, but in most cases these compositions are beautiful illustrations rather than image manipulations. The only difference with the 1960s is that the analogue pencil has been replaced with an electronic one (via Ads of the World).