I both loved your narrative and have major problems with it simultaneously. I do agree that New Agers' singular focus in feeling good and becoming a better version of oneself is both simplistic and lacks balance.

"‘Spirituality’ is defined here as that which relates to the ultimate destiny and purpose of my self-conscious existence,-"

Interesting "definition". I equate "spirituality" with spirit. Spirit is unknowable and mysterious. To understand spirit - in my view, cannot be done exclusively through logical inquiry. To attempt to define spirit destroys its essence by the nature of analysis. The parts do not equal the whole.

The question of destiny and purpose are good questions and while they have elements of spirituality - to define it reduces it to a lkinear inquiry that like the New Agers' has a goal as you write:

The true spiritual quest cannot be satisfied with anything less than ‘the very endpoint at the very end of the very last road."

This goal seems to relate to our finite existence along a goal oriented trajectory much like the New Agers' line of thinking - to feel good and improve oneself. Same thinking- different goal.

If spirituality is mystical, mysterious and ineffable, then defining it destroys its meaning.