This is an experiment. We are taking a known and common shape and moving it, while leaving open strings ringing.
This is similar with what we just did with the C shape [3 string open].
As we do this, fret by fret, we make listening judgments. Core idea: using our ear to make sonic judgement. And, using those findings to play/write progressions.
As we move the shape, we ask “does this sound good [thumbs up = resonant, full, pretty] or like a scary movie chord [thumbs down = dissonant, tense, angry]?”
We are making this judgement based on strumming it. Ultimately all of them work, but we want it to sound pretty while strumming to be a thumbs up. In live teaching settings, the result is that we agree on what is resonant and full and sweet sounding vs. what is dissonant, 99% of the time.
We can do this with any shape or configuration. Keep in mind that if a closed system [all tones fretted] sounds good in one position, it sounds good in all positions. The open strings are what create an opportunity for sounds to mingle or argue.