if you go look at the original Fallout 3 trailer, it looks and functions pretty much exactly the same as the final version.

Please read my post before replying to it. I said:

Fallout 3's E3 2008 trailer was not very misleading in that it didn't misrepresent the gameplay or graphics

The trailer itself didn't look awful. It was not misleading. The point was that even though it wasn't misleading, we still were missing information about the game actually looking like dogshit. There's only so much a trailer can show you. The trailer didn't look great, but when the game came out, we saw how bad it was.

Now Bethesda games have always been buggy, and I expect that much of Fallout 4 as well.

Why is it an acceptable excuse that their games are always buggy? Isn't that all the more reason not to pre-order them? Who knows if it will be playable on launch? Who knows how long after launch it will it take modders to fix major bugs?

It just comes down to how many variables there are inside a game of that size and scope. Something is bound to fuck something else up eventually. One can only hope that it's not too bad, but then there are always the official and unofficial bug-patches which fix pretty much all issues.

I'm not asking for a perfect game with no bugs—I'm asking for minimal QA testing. There are open world games with far fewer and more minor bugs that Fallout 3. It's not impossible. If it's that difficult for them to release a game where you can reasonably expect to finish a playthrough without a game-ending bug, then maybe they should concentrate on one platform instead of releasing it on Xbox, Playstation, and PC.

As for this... I simply disagree. I played the hell out of them when I was younger but I never saw F3 as anything other than a step up other than a few cut features, buried under a huge amount of new ones.

This may be news to you, but the number of features is not necessarily correlated to the quality of the game.