Great thread! I'm currently playing as a Halfling and I noticed most of the things you pointed out. One of the most offputting scenes I experienced (in which the giant head was really noticeable and uncanny) was spending some time drinking with Shadowheart after defeating the goblins. My Halfling's head looked a lot larger than hers, not the same size -or smaller- by a long shot.
I get that these are races that not many players pick, but it's totally possible to make these models look and move as good as the others.