How does #3 relate to the practice facility?
#3 is related because most fans under 30 years of age do not have the fond and sentimental memories of the Cowboys success that those of us over 30 have. To them, they've heard the stories but they did not witness the success we had back then, so they do not have the same emotional attachment that we have.
As for those of us over 30, it has been so long since the Cowboys won a Super Bowl that Valley Ranch's sacredness seems like a distant memory that was from a time long ago just like that of the famous Cowboys players of the 1990s and before. Since those days the team has endured and undergone many changes over and over again in hopes to getting the Cowboys back to the Super Bowl only to see failed season after failed season.
I'm sure for most of us, we will remember Valley Ranch as a key part of the history of the Cowboys organization, but its retirement, at least to me, seems like it will put an end to the ongoing damage each year caused by futility over these last 20 years which have tarnished a little of Valley Ranch's reputation for many fans.