There was plenty of "passion", especially over Quinlan.
But, the major difference is this: the families were pleading with the courts to let them end the exceptional medical care (respirators).
And, equally important, there were no family members pleading with the courts for custody so they could assume responsibility for administering food and water and rehabilitation.
In Nancy Cruzan's case, it was a feeding tube, just like in the Schiavo case. However, in different words, you've made my point. There is nothing unique about the Schiavo case except the ugly family feud. Why should the entire federal government, the state government, and various and sundry hangers on get involved in a family feud.
If it's about saving life, then all people in the same situation should be kept on feeding tubes and other life support measures. On the other hand, if it is only about this one life, then all of those who are invoking religion as their rationale for keeping her on the feeding tube are hypocrites. Why? Because all they're doing is making themselves characters in a soap opera.