Did I mention Fallout at all? No. If what you say about its sales is true, then yes, by all means, it was a failure. Perhaps it's a somewhat alien concept to you to use the same logic in two different (yet analog) reasonings leaving other subjective considerations out (in this case your blatant and badly contained fanboy-ism), but that's what, you know, people with a brain do.
And people don't get into business to get "critical acclaim" for their work. Musicians do that, not software developers. Troika received "critical acclaim" for their games, and they didn't last long because their games were commercial failures. Sorry pal, but "critical acclaim", as nice as it may be, isn't edible. )
But hey, no need to get all worked up just because I have called you on an obvious contradiction. It happens to the best of us. Or perhaps it's because I have not joined in on the PST wankfest?
Any initiative that contributes to drive a business to bankruptcy is an absolute failure. If all their games had sold as PST, Interplay would have gone down much earlier. BIS, too.
Also, I think that you would be hard pressed to find a game that "flat out didn't sell" (as in didn't sell a single copy), but perhaps there is some case.