Why might it be more useful to classify bacteria and archaea based on their morphology

Both domains are capable of sharing segments of DNA with unrelated organisms which makes genetic classification difficult

Explanation:

Prokaryotic living beings, generically called bacteria (Monera Kingdom), belong to two distinct groups: bacteria and archaea. Their differences are so significant that they can be classified as two separate kingdoms (or domains), depending on the classification system. However, both domains have a striking feature that is the ability to share DNA segments with unrelated organisms.

This makes classification difficult based on genetic material, so it would be more useful to classify bacteria and archaea based on their morphology.