I personally think it's a waste of resources to release commemorative postage issues that don't have vast common interest.I know that statement is probably controversial and we should honor historical figures, but it seems like each year there are issues to literary or scientific achievers that aren't exactly household names.
Part of a stamp's purpose is to educate. They alert you to people and things that you may not know about and offer an opportunity to learn something new. They also encourage people to pursue new employment opportunities, hobbies, research, or literary works.
Besides, how do you define common interest? Common interest varies per group, building, city, state, religion, race, etc. It is impossible to please all the people all the time. I do think they should get more import/feedback from the general public but someone is always going to get left out and unhappy with any stamp.