Are you a troll?
I mean in all seriousness, I understand the argument of improvising being the best way to play a Hitman game, I agree.
But speedruns exist a long time now, and they have become an entertaining hobby for some people. Beat the time. Beat the system. You know. I acknowledge and respect them, even though I do not see it as the ideal way to play a Hitman game.
He is not arrogant. He never said he did this first try or anything. It's a pastime for him, a fun thing to do. Testing out the boundaries of the game, the limits of the systems, exploiting weak-points and loopholes. And it actually helps development a lot of if ask me.
For example, based on what he did I can clearly see that the game (based on the tutorial missions) needs a lot of work in A.I. routines, difficulty and ability to reach targets. Plus it probably needs a lot of additional tweaking back and forth in it's mechanics.
Of course this could just be due to the beta only having 1 difficulty setting and missing various elements that the launch version will have and also due to both missions being tutorials. But if this is what it basically will be, we give our feedback on the beta. And based on that developers can decide what to do. Like if I criticize something and the devs actually changed it anyway in the final launch version of the game they have nothing to worry about, since they covered that. But if I bring up a point that they did NOT change in the final launch version then the feedback will help them to correct flaws and tweak settings.
(That being said, I really hope there is a way for us to modify detection times, number of "enforcers" and tweak the general systems on our own a little bit. Maybe Xcom 2 kind of spoiled me, but you wouldn't believe how helpful it is to correct the mistakes on your own as a temporary solution while waiting for the official fix on the developers side (also takes a little bit time pressure away from the devs if you have some mods that can give you a temporary solution)).
Like I said, I hope it's gonna be harder in the final game. Not the same way Absolution was mind you, because Absolution was really more of a "unrealistically hard" and "artificially hard". I hope they go towards a "plausible but hard" in the final version and make it easier/harder based on difficulty. I don't mind the missions being like the beta on easy difficulty, but on normal, hard and brutal they should be harder.