All of the comments on this thread have been sobering, informative, educational, and more. Hopefully not piling on here, but a couple of thoughts and recommendations:
1) Take a swiftwater rescue course (I'm overdue on a refresher). There's no substitute. Like helmets, seatbelts, and insurance, you'll hopefully never need it, but...
2) Boating has changed a lot since there was consistently good water in CO. Sawed-off boats, planing hulls, improved techniques and skills, etc. make stuff easier than it used to be in longer displacement hulls - maybe deceptively easy, especially for newer paddlers.
3) If your boating buddies push you to run something, or ridicule you for not running it, find new boating buddies.
4) Commendations to the people that were there. Sounds like they did everything right. Gotta' admit it would be hard for me to think as quickly, clearly, and objectively when it's my best buddy in trouble - something I will reflect on.
5) Deepest sympathies to the family.