Aerospace, depending on the area of aerospace you are working in, is the same as automotive. A PE looks great on your business cards and you are likely to get a raise. But, for the most part, sign off on drawings isn't necessary so you will not use your PE, and therefore seems of little value to "higher-ups." Not too mention, companies don't want to pay liability insurance for every engineer that has a PE in order for them to sign off on documents, and I know I won't pay for the insurance on my own.
I am also going to concur with bradh. The only time most people, other than the "haughty PE's," care about who has a PE is when an accident occurs and fingers start pointing.
Plus, it's fun to snub the PhD's.