Agreed. But being polite is not always professional either. For instance at times in my job I am very curt and direct, I don't be nice and polite, it's a waste. I don't have time for that, and It can come back to bite you in some areas. I don't have time for that on the job.
Personal life might be a different story for some
Depends on your position and type of job, because in many jobs or professions today, doesn't matter that you have tell someone no or be direct. It's still expected that you should be nice or polite about it.
Also, I think judging people for being polite runs the risk of putting someone down for doing their job well or denying them the right to some dignity. Many people are not in positions of power, authority, or privilege. Being polite is their way of dealing with having to face uncomfortable, difficult, and demeaning social situations. Agree with
@James - it's another way of showing grace under pressure. Yes, sometimes, politeness can be overdone or forced, which can be uncomfortable. However, if we're focusing only on perception rather than intention, it's easy to misconstrue what it means.
Almost every industry or job today is expected to use a customer service approach or ethic to interacting with people including coworkers and bosses. So, being polite and agreeable is often about job expectations and survival. It's often the case, where personal feelings don't matter and you're not paid to give your opinion, but do what is asked. Someone can see being polite as sucking up, but it may be what's necessary to keep the job and be considered a good worker. Showing dislike or disagreement or being too reluctant to go along with suggestions is often seen as not being a team player. So, many people don't have a choice. Voicing different opinions or views than what's popular or commonly accepted often gets people fired.