ZZZ is my first ever gacha. I tried Genshin recently. I abhor it's unskippable story with horrible writing, recent character design and most importantly it's terrible, terrible combat. However Genshin has one thing that ZZZ does not. It has meat on its bones. There's an overwhelming amount of things to do. Any direction you go on the map there's stuff to explore, puzzles to solve, quests to find.
Do I want ZZZ to become fully open world? No.
However a hybrid situation of Hollow Zero not being a set of corridors but instead having larger levels a la Nier: Automata would solve many of the game's issues. Limited agents would get more value as they'd have different ways of transending the map. Optional puzzles, enemy ambush sites, random elite and boss spawns would give the player a much stronger sense just how dangerous the Hollows really are than how they are currently displayed. Semi-open world would bring back a plethora of more casual players. We'd have more reason to use our agents to explore.
I love ZZZ but every patch after the first couple days it feels there's a drought of content. Log in, scratch ticket, drink coffee, spend 300 energy, log out. With some minor tweaks, if handled correctly I'm confident a Semi-open HZ would be a great addition to the game.