Although I am not Catholic, I have had a great deal of admiration and respect for him over the years.
I have a theory about the course of his medical treatment over the last few days.
It seems to me, from the video clips shown, that he was suffering, and frustrated over his inability to speak. I believe that he realized that he was no longer able to carry out the duties of his Papacy, had only a few more months to live even with extremely aggressive treatment, and during those months, would not improve significantly, or be better able to carry out his duties as Pope.
There has been much speculation over the last year as to whether he would resign for health reasons, the first Pope to ever do so, at least in modern times. I believe that he would never choose to resign, as that would set a precedent for future aging Popes. I don't think that JP2 would ever want to set such a precedent.
So, I believe that JP2 has made a deliberate decision to not seek super-aggressive further treatment, and to have it end this way, now. I realize that I am totally speculating, and if I have offended anyone, I apologize in advance.