There is a Terry Kath biography I watched recently where his wife is interviewed, and she states he was cleaning his gun, not knowing it was loaded, when it went off. I too had always believed it was Russian Roulette gone bad. Even though the truth has come out, it's not any happier an ending. Yes, Terry Kath was one of the great guitarists. Imagine where he could have gone with that talent. At least we have a few albums that show how amazing a guitarist he truly was.
Whether in hindsight it is true or not, I recall it being reported at the time of his death, that his last words were something to the effect of, "Don't worry, it's not loaded."
It was a tragic loss.
It's hard to say that you're happy that an urban myth you once believed turns out to be wrong in this case - i.e., I want to be happy it wasn't Russian Roulette, but, as you said, the truth is no better.
You know, I remember another interview with members of the band, and they backed up the Russian Roulette story. It might have even been a "Behind The Music" show on MTV. Oh well - either way, he's just as dead, and it's just as tragic.