Q: What are the qualities of the risen bodies of the just? (What will the risen bodies of the just be like?)
Q: WHY will our bodies rise from the dead?
A: God wills the resurrection of the body, in order that the soul, having done good or evil while united with the body, may also be rewarded or punished along with it. Hence, the bodies of the just will rise to share forever in the glory of their souls, and the bodies of the damned will also rise to share in the eternal punishment of their souls.
Jenny Mary left a wonderful answer at the comments box yesterday. She pointed out that we, humans, created as Body and Spirit is NOT 'complete' when our bodies and souls are separated. God, in His infinite mercy, desires the full plenitude of Blessedness for us in Heaven, will raise our bodies, so we will all have our own bodies and souls together again. Please take the time to read her full comment.