I just want my own office. That's all. I'd be pretty okay with going in if I had my own office with 4 walls. First job of my career, they told me I would have an office of my own. First day I come back do for full time (I had interned there too with my own office), they tell me they're switching buildings to go open office in about a month's time. I got a precious few weeks with a personal office, and then it was all…
An open office is cheaper to manage for the company. It's all about the bottom line. That's most likely the biggest reason it exists.
1) The notion in architecture that open plans, by literally removing barriers, figuratively remove them and create a more open and inclusive office environment. This is a popular belief in the biggest architectural firms in the world, even though the principals at those firms all have luxurious private offices.
2) Recently some offices have flipped to open plans to accommodate hybrid working. E.g. allowing employees to WFH 2-3 days / week but then expecting them to hot-desk when they come in. This reduces the total footprint required, which can reduce costs...except many firms are using the saved funds to enhance the office in other ways (more natural light, better furniture, plants and fountains, catering, etc.) in order to attract talent.
Gensler has published a lot of this research and positioning publicly in reports and in their podcasts.