A little history is in order here. This "tude" is not confined to bluegrass but has been part of folk music scene, jazz, blues and any other kind of music you can think of. There was a time in folk music where some academic types would call you on the carpet if you didn't play the Carter Family style exactly like it was on the record. The traditional jazz scene is rife with this garbage. Some say jazz had to be just played by black people. Others said if it wasn't done before 1930's or so, it isn't trad jazz. Others said, such as the late Leonard Feather alleged, if it ain't be-bop or modern, it's crap.
There is a reactionary tinge to some members of the bluegrass community maybe in contrast to the left-wing influences of the folk revival. Lots of rebel flags pop up at bluegrass concerts. Here's the deal. Most of the people who play music with "tudes" are amateurs and this is a double-edged sword. On one hand they don't have to do stuff to their music to make it sell. (They have day jobs). On the other hand, they don't take into consideration what the needs of their audience are. If they were pros, the audience would let them know.
I think what is required is a healthy respect for the music that you play which entails studying it at some length but keeping an open mind that there are many forms of music that are valuable.
When the Weavers were working in night clubs and venues across the country prior to their blacklist, Pete Seeger's mission was to widen the audience for the recognition of American folk music. I think he successfully did this without being a cultural part of the traditions that he presented. They couldn't be "reactionary" to make that work.
When I traveled South to collect folk music and share with others, I didn't come across any of the "tudes" that I've seen lately at bluegrass events. All of the rural people that I picked guitar or banjo with were pleased to hear all kinds of influences and at the same time were happy that I was interested in their music and it's cultural background. This "precious" attitude that you describe has been in all kinds of music and serves not much except to salve the egos of those who carry this baggage. The music remains what it is.