I've just quickly read the comments here, and noticed a lot of arguments revolve around "how realistic" the game "metadata" should be. I see both map & instinct as metadata features.
My personal opinion is that "how realistic" is simply not part of the equation. Un-realistic "things" are found all over the place in video games, even in previous Hitman games.
Plus, a lot of seemingly "unrealistic" game mechanisms are found in some of the most successful and fun games out there. E.g. boss fights in Metal Gear series are known to use very simple mechanics. Bosses move in an initial pattern, which you have to become familiar, then when their HP goes down they change into a more complex pattern, you need to familiarise again! Now... this is extremely unrealistic, but also very fun! I don't put stock in "realisticness" in video games. I put stock in "fun mechanics"
So in line with that, what concerns me is: what makes Hitman an engaging & unique experience? To me, the answer is: "WHEN I HAVE TO USE MY BRAIN TO SOLVE MISSIONS"
If I am given exclamation mark on the map, denoting something special about say "the left-top corner of a room". Then I need to explore that "corner of the room". Even if I get to that room, I might still have to scratch my head and have a play around. This is FUN.
If I use my x-man goggles and see exactly that it is the drink that's on the table that I need to poison, then, I don't need to explore anymore. I know exactly where to do what. This is NOT FUN to me at least.
An even MORE FUN way of giving hints, is to perhaps highlight an entire room, instead of locating with an exclamation mark. This way I have to enter the room and explore it fully. USE MY BRAIN, try different things and come to my own conclusions.
Perhaps this is the "unique niche" which Hitman occupies: "the game which lets players get lost and find their own way and get a sense of accomplishment". So I would suggest to the devs at IO to promote this kind of gameplay regardless of whether it's instincts or maps or whatever. Simple create a mechanic which promote: exploration, getting lost, going back and forth, scratching your head, solving puzzles, finding distant correlations, etc.