That is a concern, but even if the whole game were to be opened up, the game will still end up shipping with some bugs. Less than what it has now, probably, but there still will be bugs.
People keep complaining NOW that they have to restart their saved games after every patch, and that the saved games won't be compatible with the full version. I'm not one of them, but after all these months, and hundreds and hundreds of restarts, I'm burning out on Cyseal, and I basically ignore all the quests Cyseal offers - I skip through the dialogue without really reading it because I've read it so many times before.
If the rest of the game were to be opened up now, and with me knowing that a reset is coming, I don't think I'd go see it. I still want to see fresh experiences in the rest of the game, I don't want everyplace to end up being dulled by familiarity.
Practically speaking, that kind of thing has an issue with the two/three-week patch frequency. Larian would have to choose between making their saved games compatible - limiting the amount of changes they can make, -OR- having a much, much longer time between updates to give players time to play through all the content, because the game is long enough that a person will have trouble completing it in two-three weeks of average play. They wouldn't get a chance to see the later area bugs in much detail anyway because so many people won't be getting there before the next patch and reset hits.
