It would be nice to "pretty print" field labels in the formatter settings instead of machine names. The problem with this is that a field can have many labels, when attached to different bundles.

Most of the time however, I believe a field will have a single label, or maybe two, in which case the a "Label 1 / Label 2" approach will work just fine, look much better than machine names, and be better UX. To accommodate the rarer cases with many labels, an admin option could be provided to return the formatter to use machine names.

I'll probably do this myself at some point, but patches are welcome.