most large companies have no problem keeping the game(s) 99.9% bug free..
you have remember a company liek blizzard for instance, can delay a game for another 6 months without having to worry aobut bills, where as smaller companies are on a game to game basis and really do have to worry about how long they delay a game.. i dont know how larian fits in here.. but i wouldnt be suprised if they just cant sit on the game to long without having problems with money..
this is also why having a good publisher can help.. the large publishers have QA departments as well (though, i have never heard of a publishers QA department being anywhere as good as the inhouse QA, due to the inhouse's familiarity with the game, and amount of time they spend testing it..) .. plus the ability to support the company if they need to delay for a certain amount of time to clear any major bugs..
i think the biggest problem thus far for BD is that some of the patches created newer and bigger bugs.. i played for a while under 1.32 and had no problems.. i saw some of the bugs.. but nothing that effect gameplay (no crashes, or anything of the like.. just like, mislabled items.. which i can deal with..) .. but it seemed that with 1.41 and 1.43 now they have brought in some major problems..
currently i am plaing 1.40 and having no problem... sure some mislabled items.. (bone spear i think still looks liek a ring.. ) but no crashing or anything like that..
just high-demand for new patches and they get rushed i think.. and not 100% tested for QA..