Dear ACLumsden,
Many in this video, I believe, are perhaps less than five years into singing the chant, and then on a part-time basis. So your encouragement is most valued, especially as a veteran of the art!
The first years are so very critical in building up the belief that one can actually sing these more complex propers; but, also as critical, once that belief is secure, to use the acquired textbook technique as a point of departure to a more perhaps 'passionate' rendition (both in solo and ensemble chanting). To sing with understanding, and allow the texts to be illuminated by the melody instead of shrouded by it, is key IMO. I hope this makes sense.
I share your weariness of the philosophy you describe, by the way, which often unintentionally shrouds the text by an overly dogmatic performance methodology.