I agree with your points regarding police and their misuse of power, the social repercussions of our destructive over-prosecution and incarceration systems, and even that minorities (and especially black people) have suffered from restrictions on housing, access to medical care, and educational opportunities.
However, I differ in opinion to the reasons why.
Let's approach this semi-Socratically and start with a question: why is it even remotely arguable that our country's first black president can be said to have done more for, and tried harder to pander to, illegal residents of this country than he has for our own black citizens?
Another question: why are the republicans fielding presidential candidates that are supporting amnesty for illegal aliens when conventional wisdom paints them all as racist pigs who hate Mexicans?
I believe the answer to these questions is directly related to the reason why black Americans continue to suffer in our country. Namely this, when a group remains flexible in their political approach and support, they will have the advantage of participating in and reaping the benefits of the political policies generated by both the democrats and the republicans. However, when a group remains singlemindedly dedicated to one party, either the democrats or the republicans, and is antagonistic toward the other, their ability to maintain meaningful representation and to effectively influence the political landscape is destroyed.
Just look at Christian religious groups and individuals in the U.S. In the past they had great control over both parties. Now as the faithful lapdog of the republicans, they get to watch while their Armageddon approaches. Gay marriage and rights legislation are passing in state after state, and even some of their republican leaders are beginning to entertain the idea of coming out for gay rights.
Similarly, black Americans have watched as their infrastructure, business opportunities, and educational prospects have dwindled to the point of permanent subclass status, all under the care and feeding of the democrats they elected and that overwhelmingly control the ghettoized landscapes where they are increasingly forced to live. They watch as their children are undereducated and let their leaders prevent any competition in their school systems and make underperfomring teachers impossible to fire. They see businesses retreat from their neighborhoods in droves, and continue to elect candidates who raise taxes on business. They vote in leaders that offer social programs, instead of economic opportunity.
And who can blame either party for taking these people for granted? These black peoples and religious zealots are almost exactly the same. They have proven time and time again that they will sacrifice their personal integrity, compromise their beliefs and ethics, and whore themselves without reservation to their dedicated political party, regardless of the abuse and distain they are treated with, without a care for what those parties do to their closely held beliefs, and without a thought for the future of their progeny.
So, let's contrast the Hispanic voting block with the two sad-sacks I just mentioned. They appear similar to both groups actually. Religious, maybe even overwhelmingly so to some. A minority with a history of abuse and disenfranchisement. No outright slavery in their past, but if you knew how hard undocumented produce workers had to labor for less than minimum wage and with no benefits, well it's hardly above slavery at that point. And yet, here we have two parties competing for their vote. They haven't thrown their hat in one ring and started the aggressively self-enforced indoctrination of their children and peers toward one party, punishing those who dare to be different with ostracism, vituperation, and even violence. Hell no man! They are doin it right, esse! They have both parties eating out of their hand, offering them everything they want. I mean really, our first black president decided to (ostensibly) violate the freaking constitution, defy congress to their face, and singlehandedly stand up for millions of illegal aliens by wielding his presidential power like no one has ever done before. But when asked about the plight of African-Americans that led to the recent riots, he totally cops out with a lame ass excuse, saying it can only be fixed if everyone wants to fix it, and everyone has to work together or nothing will happen; and people fucking accept that shit?
So, as you can see, I feel expressly that these points are all data leading to the conclusion that political devotion Is political suicide. Make both parties vie for your affection and you can have just about anything you want.
Need more proof? Look up all of the vastly successful companies that donate money to both parties. They get everything they want.