Hehe, Medieval 2 is ironically one of the most polished new releases I've gotten my hands on this year, way ahead of Sid Meier's Railroads, Gothic III, and Age of Pirates: Caribbean Tales (arguably the buggiest game to ever occupy space on a HD of mine).
1) My instinctive response is that this isnt all that new. Daggerfall, Darklands, Ultima IX, Elite II, Frontier: First Encounters... I've had a lot of experience with crappy first releases, and we tend to forget . There is one difference compared to the past though, and that is that devs and publishers feel that since "everyone" is online nowadays you can expect your customers to download patches to a larger extent. In a way this makes it easier to meet deadlines. It would however surprise me if it is more economical overall to release a buggy product, as patching requires resources that could have been devoted to creating new products.
2) C. Unrealistic deadlines are symptoms of poor project management
From my experience with other areas of software (or other) engineering you have three groups involved. The marketing/sales people who push for a deadline but have limited grasp of the capabilities and difficulty of technology, the creative people who come up with great concepts but tend to underestimate the difficulty of implementation, and the engineers/programmers. It's the second or the first group that plans the project, and the first one that sets the deadline.
Then there are some problems caused by the rapid improvement of gaming technology. If you withhold your release for too long then your technology (the graphics engine for instance) might be obsolete. Couple this with there being a few highly preferrable release points in the year (meaning that it is imperative to get a game out before christmas or some other holidays) and you have a situation where a missed deadline (which often is set by external factors rather than by a realistic estimate of how long it would take to finish the project) could make the project a pure money sink...
Finally there is the fact that games do become bigger. Customers except more content with each new release, and more refined graphics/gameplay/AI/whatnot. These improvements do require more manpower and a stronger cash flow, which makes it more costly to miss a deadline.
3) Of course not. But the world isnt fair...
4) It will probably get worse. I can see two ways of reversing it. First reviewers (that do help quite a few buyers make up their mind) need to be more critical towards technical problems in games, and reduce the amount of uncritical raving about unfinished preview versions. Second we as consumers need to start using the great power we have in a market economy. Namely that of voting with our feet. We put up with way too much crap from publishers and developers.
Since I dont expect review quality to go up anytime soon (to me it rather seems like reviewing is following general trends becoming more tabloid-like outside the niche channels) it is up to the gamers to bite the bullet and deal with this.
I'm not sure consoles will remain problem free either. Some titles (such as Morrowind a few years ago) already took bugginess and crashing into the console world.
We are also seeing consoles with online capability now, making it possible to offer patches to console games as well, offering the same kind of temptation to devs. But maybe the fact that the console market have more "joe blow" ordinary consumers that have less patience with this crap can moderate that?