This is Joseph

I hadn't been thinking about density like this, but here is a good point about LA:

LA suffers from the too-dense-but-not-quite-dense-enough problem (overall it's a very dense city, but with a kind of uniform density that is a bit difficult from a transportation perspective). 

I have generally hold that density is a pure good for transit, but it seems obvious that "destinations" would make things work a lot better than thousands of point to point connections.  The former (New York density) seems to make transit look super efficient.  But if you are relatively dense everywhere, that almost makes a cab/uber style of transit look efficient.