First, I'll preface this entire response by saying that I don't mean to anger you (you sound upset in this post). I am merely making comparisons and offering my thoughts.
Now, onto this first point - I'm not sure what you mean by "urban core." I don't envision commuter rails going out to Columbus to reach Atlanta necessarily. I'm talking about where the majority of people are coming from to get into the city. Gwinnett, Cobb, and northern Fulton counties are the prime regions where these type of transit options would work. And regarding your other point about car-oriented system, I think you're making my point for me. This country has relied on that mentality for too long, and before oil and gas prices exponentially grow (which really isn't too far in the future, as many economists predict we have already reached our peak oil productions and that oil could hit $100/barrel as early as in a year), we need to develop better and newer strategies for mobility. There is no reason to shrug off or ignore these issues by simply saying that Atlanta is not like NYC or Chicago. The traffic situation here is horrendous and has a detrimental effect on all, whether it be through air quality, stress, economic strains, etc.
Again, I will disagree with you here for the reasons I stated earlier and just above. The excuse that Atlanta is not like other cities can only be used so far. And I don't understand what a "core" city has to do with anything. You wouldn't consider cities/areas like Alpharetta, Dunwoody, Sandy Springs, Smyrna, Marietta, Kennesaw, Norcross, Peachtree City, Fayetteville, etc. as regions where a large amount of people live and commute to Atlanta for work?
I don't understand why you would prefer to spend money on a more asthetic element of this city that has little if any real gain for the people in the metro Atlanta area as a whole over working for a better integrated city. That to me is just wasteful.
Look, streetcars would be attractive, but that's about all they would do. They would still traverse down busy roads, causing congestion and not relieving traffic while moving a limited amount of people. If the proposal for this were to come for referundum over, say, expanding commuter rail options to nearby suburbs, I would quickly vote "no."