It is somewhat difficult to respond to your statement due to the length of it and the huge poutpouri of points you make, but I will try.  

I want to stay focused and make, specifically, a case for the inclusion of a reference to the desolate state of urban Detroit in the introduction to this article.  First of all, though I hate to flash credentials, let me point out that I am not some urban partisan of one city or another: I am a graduate student in urban studies, and my goal both on Wikipedia and in my academic career is to understand and describe urban processes.  I agree with you in as much as most articles on cities on Wikipedia are exaggeratedly positive: alas, but boosters have their way on these topics.  Most major city articles could use to be more critical.  The Detroit one is simply one glaring example of the difference between real life and its presentation here.

You contradict yourself multiple times in your response (and, for the love of god, stop tinkering with it!  It distorts the appearance of our conversation).  How can you claim that New York City is "five cities" (only two of the boroughs were incorporated as cities before joining into a single city in 1898; today, they are tightly bound by transit and employment patterns) and yet demand that the unfocused, sprawling Detroit metropolitan area be considered one city?  How can you stick to an arbitrary statistic about the wealth of Oakland county, and yet deny the significance of the fact that most statistics (even those that address metropolitan areas and not just urban municipalities) place Detroit near the top of the list of the most dangerous? 

The point that this article needs to make is obviously not that the Detroit metropolitan area is poor or that it is deteriorated; both of those statements are obviously false.  Rather, it needs to make it abundantly clear that the metropolitan area contains inside of it a vast segment of abandonment and crime that continues to be in decline for over five decades.  The existence of upper middle class suburbs of relative wealth and low crime do nothing to make the deterioration of the urban core less notable; neither does the recent redevelopment of a piece of that core.  

I must point out your focus on New York City is rather misguded  its deterioration and crime are now of a historical character; if Wikipedia had existed twenty years ago, one can only hope that it would have focused on NYC's urban wasteland character more.  In response to your other points, I would like to invite you to join me in patrolling the self-promotion of all city articles on Wikipedia.  You are certainly right, many of them do deserve to be less positive.  Let's start with this one.  

But, alas, I doubt that you will accept my invitation.  The history of your edits shows you spending much of your day chiseling away at the language of this page to make it more favorable towards its subject; are you paid to do this by the city's tourist bureau?  In any case, I can only hope that the casual reader would know to pay this page same kind of attention they direct to the boosterist propaganda spread by local town publications.