Part of the problem for engineers who want to move into marketing is the old "Left Brained : Right Brained" dichotomy.
We are all a combination of left and right brained traits, but engineers tend to be more left brained. They are more detail oriented and logical. They reason through things in a step-by-step fashion. They see problems as a series of dots to be connected sequentially with a line between each dot. If they were a fisherman, they would bait one hook, drop one line in the water and catch one fish. They tend to play it safe and follow the rules. They are practical.
Marketers tend to be more right brained. They are big picture and intuitive. They gather random information together and weave it into a solution. If they were a fisherman, they would cast a net into the water and catch all sorts of fish. They tend to take chances and bend the rules. They are creative.
By now, you are probably thinking, "But we are talking about technical products. Engineers need to be able to talk to engineers. If the customer is left brained, shouldn't the salesman be left brained?" It is true that the technology marketer must have a good technical aptitude, but I assert that "marketing is marketing." A good marketer will know how to sell the product to the customer, whomever the customer may be.
A few examples will clarify this.