@Andy Fletcher - you are part right
I bought FO3 and although I generally loved it as a game, I was very disappointed with the serious stability problems.
So, when FO:NV came out I waited a while before buying it. This meant not only did I wait until the serious bugs were squashed but I only paid something like £14 for it rather than the full price of £30-£40. I think £14 for the current (still buggy) product is about fair.
OK, I bought the game, which helps Bethesda's bottom line and sales figures, but by a lot less than if FO3 had been mostly bug free. Equally so given the bugs still present in FO:NV I will not buy the next FO title until it has been out some while and is down to a price I would be willing to pay for a game I expect to be as buggy as FO3 and FO:NV.
The same goes for Skyrim (Elder Scrolls V - also by Bethesda) - I am really looking forward to that game, but I am pretty certain it will be a buggy mass of crap on release so I'll initially keep hold of my hard-earned, probably until the January sales (Skyrim is released 11/11/11) when it will be at a price I am happy to pay.
So, make of that what you will, I suppose. Maybe Bethesda will learn, and maybe they won't, but whichever way you look at it me paying £20 less than the retail price for the game has to hurt the developers: either some or all of it comes off their profit so they will get less cash directly or the reduction is borne by the retailer who will purchase fewer copies of the next release. Or a mixture of the two.