Is constantly focusing on past oppression counterproductive?

I’ve heard the argument before that incessantly reminding a community that they were or are oppressed works as a de-motivator, convincing people their situation is hopeless, that they can never succeed because the “system” is against them. I’m reminded of a Hispanic friend of mine who took a Chicano Studies class in college but soon dropped it when it seemed to him to be nothing but talking about how oppressed the Chicano community is. He found the pessimism and negativity off-putting.

Is it true that focusing on an oppressed status demotivates? What has been your experience? Do you think we need more messages of hope, that we are too mired in the oppression and misdeeds of the past? If so, how can we avoiding “sanitizing” history?