I'm not sure what people, teachers, or philosophers you're referring to.
The term comes from the Sanskrit, and it was very consciously termed AD-vaita, NOT two, rather than simply eliminating distinctions.
Samadhi is specifically referred to, in Advaita Vedanta, as a potential deviation from non dual awareness. And to say we are sometimes in "duality" and sometimes in the "non dual" is to confuse the meaning of non duality.
Since you are concerned about intellectualization, I'll put it more simply.
"I see a tree."
It seems obvious to most people that "I" refers to something "here" and "tree" refers to a "real" object, over there.
When the 2022 Nobel Prize winner in physics, Anton Zeilinger, states that we have no direct contact with an alleged "physical" world and that all science starts with perception, he is getting very close to what the Buddha meant when he said, "in the seen, let there be just the seen; in what is heard; let there be just what is heard."
This doesn't involve any "woo" - it doesn't mean you're in some special "state" of "samadhi" or "flow" or anything like that. Anyone looking will of course see a person and a tree. But seen within a non dual context, the "knowing' of whatever occurs in experience is radically different.
As far as ethics and discipline, I'm not aware of any GENUINE non dual teachers who dispense with those.
For a genuine practitioner and teacher, you might look at the works of B. Alan Wallace. Perhaps the simplest, briefest text is 'The Attention Revolution." He describes a path to samata (not the same thing as Samadhi, if by that word you mean "trance" which indeed is temporary while living in physical bodies.
Samata is a state of complete mental silence. It remains in the background if thought is needed, but as one goes about one's life, all 24 hours (even in to stage 3 deep sleep if one is advanced enough) and even the most active mind does not cover over the background Silence.
Wallace emphasizes again and again a thorough foundation of ethics, love, compassion, kindness, etc - and in action, not just 'feelings.'
When I took a workshop with him some years back, he noted that even the completion of samata training is not yet non duality. When the mind is completely still, the body deeply relaxed, one turns one's attention 'around" and looks (not asking "mentally" but looking deeply) and inquires (non verbally) what is it that is aware?
Swami Sarvapriyananda has hundreds of videos on YouTube explaining the same thing in the Vedantic context. Llewellyn Vaughan-Lee explains this in the Sufi context and Father Keating in the Christian (drawing on Thomas Merton).
Merton himself had his first non dual realization on a street corner in Lexington, KY, and always emphasized this was something completely consistent with everyday life. Maybe the best Christian example is Brother Lawrence, in his 'Practice of the Presence of God."