I remember back when I was a kid when Ruffian had to be put down, and how devastating that was. I think the difference here is that I think we were more prepared for this, even when Barbaro was doing well, there still was a sense that it was an uphill battle.
Frankly I felt they were trying to improve horse medicine using Barbaro as some sort of experiment for the future. Which in my mind is a good thing. They have to start somewhere. It is so sad that so many great horses have to be put down for what to humans is a minor injury.
I hope the docs. did learn a lot and while the result with this particular horse was not as hoped for they did gain tons of knowledge from him over the last 9 or so months.