Do we need a physical body to unfold spiritually?

If evolution continues on the astral and other inner planes, and is in some ways more advanced in these realms, then do we need a physical body at all to unfold spiritually? Is it perhaps an unnecessary burden of flesh? According to classical yoga precepts, you must have a physical body in order to attain nirvikalpa samadhi--the highest realization of God, the Absolute. This is due to the fact that on the refined inner planes only three or four of the higher chakras are activated; the others are dormant. For nirvikalpa samadhi, all seven chakras, as well as the three major energy currents, have to be functioning to sustain enough kundalini force to burst through to the Self. The very same instinctive forces and fluids which generate material involvement, uncomplimentary karma and the body itself, when transmuted, are the impetus that propels awareness beyond the ramification of mind into the timeless, spaceless, formless Truth--Siva.

-Satguru Sivaya Subramuniyaswami

http://www.himalayanacademy.com/study/mc/daily_lesson_html/lesson_349.shtml