כי הממון שאדם לוקח עם אשתו אינו ממון של יושר, וכל העושה כן מקרי נושא אשה לשם ממון, אלא כל מה שיתן לו חמיו וחמותו יקח בעין טוב ואז יצליחו
רמ"א
(Yes I know I only quoted part of it.)
ETA: So that this shouldn't be taken out of context, the Rema is referring to arguing over promised dowry amounts. But, we do see from here, that even if it is promised, it is not considered Yoisher to expect it and demand it. Especially when parents are "forced" to give it, be it from "the system" or otherwise. Rather, the couple should be grateful when parents chip in, be it some money towards a down payment down the line or some other thing as the parents see fit and can afford.
It is close to an ultimate disrespect to a parent to demand money and exposes the true character of a person.