The reason is simple on why they dont do any live stuff from These Days, they are all difficult songs to sing. Going through the album, the following have either high notes, or loud yells in them -

Hey God, Lie To Me
These Days, Damned
My Guitar..., Hearts Breaking Even
If Thats What it Takes, This Aint a love song
Something to believe in

Id say the easiest songs to sing off it are Diamond Ring, which they do a bit, Something for the Pain (which they regrettably never do), Letting you go.

Songs like Wild is the Wind, Dry County, Living in Sin, are also ones they rarely do now due to limitations. Its a shame....if only we could go back 12 years.