Your arguments have gone completely off the rails- everyone in Addison is rich, so they'd just drive their cars everywhere, but the poor also live in Addison, so they don't need transit to get to their jobs, and if we *really* wanted to improve mobility for the poor, we'd build a line through the least dense and most expensive real estate in Dallas county. What?!?
Do you not know where Addison is? The poor who commute to Addison live at Valley View & 635, which is south of Addison, not E/W. And then more poor people live south of downtown, not E/W of Addison. So a N/S line up Preston (not among the least dense parts of DFW at all) would allow them a direct route to Addison, which you feel it is important for them to get to. Without a direct line, they would have to take Red or Orange to up to the Cotton Belt and go E/W, which would take forever. Along the Cotton Belt line, the middle income people have cars and can easily take any of many streets to get to Addison (or anywhere else along the line) which is why far future ridership projections are so low.
And no, you are wrong about "new urbanists" or whatever. DART should support dense areas or they should build where future density is planned/forced through zoning. If that's downtown, then great D2 is great. If it's Addison great. Current projections and projects say that it is downtown and not Addison though.