Given how little we know about the game, it's hard to know what's thematically appropriate. The trailer implied cyberpsychosis was going to be a big issue, and the only two forces involved were a a civilian cyborg that's disassociated, a bunch of dead civilians, the news, and the police force... and that cyborg was apparently recruited into that police force. If you're not expected to ever pick stuff up in combat, if the game is treated as you being part of a police force, then a super detailed milsim-like inventory system makes sense as it's a tactical choice you make once.
If the game is more open world, if you're expected to go where you please, then an onerous inventory system that demands you constantly re-evaluate whether you can pick something up or has you constantly redressing just to cross the street simply won't work. People here may be complaining about a lack of realism, but that's a mild, niche complaint. Absolutely everyone hates a game that takes you out of the action to fiddle with a mouse-driven UI to remind you how "realistic" it all is. Because obviously nothing is more realistic than spending ten minutes deciding whether you can pick up some ammo or a candy bar or not.
This is what these games with complex inventories have in common, you don't actually use them very often. You're supplied by HQ, acquisition is abstracted away and not something for you the player to worry about. Sure, you could pick up a random rifle if you so desire, but the one you have is better. The only one you'd want to pick up is the one that has ammo lying around, and swapping out a single weapon and ammo for another doesn't make the clunkiness of the inventory screen that apparent. I mean, how long does it take you to gear up in ARMA? Can you imagine doing that constantly? Fiddling with the inventory is probably the worst part of games like DayZ, as your character magically becomes unable to respond to their environment because you're in a mouse-driven menu and that means your entire body is paralyzed while you try to eat some jerky.
Complicated inventory systems aren't necessarily more realistic, they're just more fiddly. They can cause dramatically more unrealistic behavior compared to a game that abstracts away inventory management depending on the genre. This is an RPG, there's going to be things to pick up and money to make and bodies to drag to chop shops. Milsim inventory management is going to go over about as well as any grid inventory in any other RPG, whether or not the little squares want to bitch at you about whether you're allowed to put that item in there.
Cyberpunk 2077 is going to be more grounded than a fantasy RPG, sure, there's not going to be any magical potions or teleportation spells. But if it's going to be at all like the Witcher 3, which seems likely given that they probably want to reuse as many system as possible to be efficient, it's not going to spend it's time constantly telling you no, you can't have nice things because your ammo belt already has a candy bar in it.