It's a big surprise because usually, we hear about declining health before someone dies. He was selected because he was the only civilian, smiled more easily than the others, was possibly the best-looking, and had emergency experience in Gemini 8. His soft feminine face soon deteriorated into a fragile mess. He hid from interviewers all his life despite lecturing in front of college classes. He sullied his reputation in his last years with silly anti-Obama testimony at kangaroo court congressional hearings.
You won't find those personal impressions on the internet. It's like newbies looking at Walton's stats and saying he wasn't in the class of Chamberlain or Jabbar. You had to be there.