Gersen: not because it increase their sales one anything but because : they expect peoples to pre-order their games (sometime by adding "exclusive" DLC that you have to pay for if you didn't pre-order),
A demo won't be done in time for pre-orders, not even close. Even if it could be done (and it can't) the chance the final product would look anything like the demo is relatively small.
Gersen: they impose and enforce reviews embargo up to release date and they want to prevent second hand sales
If this bothers you (and it's fine that it does), don't pre-order, seriously, it's easily solved.
Gersen: and they want to prevent second hand sales
Not all of them do, but let's suppose they do, why do you think they would want to do this? To make more money. Demos will only cost money, and in too many cases will actively deny you sales. You're seriously arguing "because they want to make more money they should do something that means they will make less money!" I'm not sure that argument is gonna fly, logically, in the board room.
Gersen: Concerning "sales data" that always make me smile,
Yeah, because in reality the data says they make tons more when they release demos so now they don't want to... You're comparing a situation with a party who has high motivation to lie on a subject with one where it's not apparent that they do.
Gersen: how can they really determine the real impact of having a demo or not
The same way they do other market research. Just because you don't always like the result doesn't mean companies don't do it and it doesn't generally (more or less) work out.
Gersen: So working on day 1 DLC once the game is gone gold doesn't detract from the final game... but working on a demo once the game is gold does... wonder how that works...
Yes, unless you wanted the demo well after the game launches, it has to go through certification too, which means you gotta get it done earlier. This is why on XBox 360, a platform that still manages to have more demos than most, non-XBLA games frequently get demos only well after the game has launched. Demos will often take a lot longer than a DLC to complete, at least that's what I understand.
Gersen: far from being the universally acclaimed game some pretend it to be.
If you can find another game that multiple reviewers with a wide range of audiences have called "the most important game in a decade/ever" knock yourself out. I'm saying this knowing you probably can't. Not everyone has to agree or even think it's a good game for it to be true. If I sat down a bunch of modern reviewers and made them watch Citizen Kane you really think they'd all like it? What about Psycho? Did all reviewers like them back when they came out? Beating this drum "not everyone liked Spec Ops: The Line" is just dumb. I don't even know if you played it, but I know a wide range of reviewers who did and were stunned by it, some them very thoughtful people. And if most of them are saying the same thing, that's good enough for me even if whothefuckareyouanyway.com didn't rate it highly.