You bring out some interesting points:
1. That there is a lack of Derech Eretz in our generation starting at least twenty years ago. I don’t think such a thing would have happenned when I was a kid. But, even some shuls nowadays this wouldn’t have occurred. I know the Rebbitzin of my shul makes sure every lady has a seat!
2. Not speaking out then to whomever -to complain and just bottling it up inside of you, has done nothing but cause you uneeded anguish. You proved the point -Never bottle up anything inside!
3. When did it become more important to listen to Megilla than keep Derech Eretz? I find many people who have every chumra on every D’rabbonim but keeping D’oraysahs of Bein Odom L’chavero is non-existant! Who was Mechanech these people?
Everyone please remember, even if you yourself have Derech Eretz, you should make a Mechoh (protest) if you see someone not doing what they are supposed to. My mother sometimes can’t believe certain behaviors. People jumping into a parking space, while she was waiting. Not letting her go ahead of them in line, being that she is old and only has a few items.