You can look at that from another angle however, the studio imposed an embargo where you can give a review once you have completed the game, fair enough as I don't think it's fair for a reviewer to spend just a couple of hours and come to a fair verdict, however if a reviewer plays 9 hours or so into a game then I personally feel that's enough time to get a feel for the mechanics and feel of how the game plays, of course with an intensive story driven game you could argue the ending will be important, but still in this case I feel the reviewer was not enjoying the game and did not want to comply with the embargo, so the correct thing to do IMHO is rather than score it, technically lying saying he had finished it, he chose not to rate the game giving it a less than perfect score, now considering on here how many are up in arms over any negative comments this game is receiving you would think this was a blessing he did not chose to finish his review.
It is completely fair to have story completion as a requirement for a singleplayer game.
In fact, that should be a given and not something to be considered as "imposed", as you state it. That already says a lot about your attitude towards the game.
9 hours for a 30+ hour game is laughable to make a final judgment.
If anyone feels different, they definitely shouldn't be a professional games journalist.
Also, nobody cares about people giving low ratings unless it's unfair.
So, if 80% of the professional reviews give 80+ scores, a 3.8 or whatever the lowest score is, is too drastic of a drop. IGN's 6.8 isn't that far fetched, tbh.
The only reason people are "up in arms over any negative comment", is because said negative comments completely dismiss 82% of the reviews and accuse those reviewers of being paid, while only validating the one 6.8 and one 3.8 reviews to push their hate campaign against Kojima or PS4 exclusives.
The majority of people in here are level-headed and reserve judgment until they play the game themselves, instead of certain users who carry their pitchforks into every single DS thread for the past week.
Guess objectivity is too much to ask for on forums.