The issue isn't open floor plans or private offices. It's quality of design, and indirectly hipsterism.
Good open floor plan designs are driven by acoustics and sitelines - management of audible and visual distractions. Yeah, staining the concrete slab and exposing the brick wall and using the metal pan and joists of the floor above as the ceiling and hauling in oak library tables as desks, just echos "lookie here, we're rebellious and unconventional." Then again everything echos. That's the pysics of sound meeting hard surfaces and since the echo reaches everyone, everyone will be tempted to look.
Architecture is sometimes said to be the world's second oldest profession - or the oldest when architects talk cynically amongst themselves about the nature of actual practice and dealing with the clients who pay them for their special talent...but anyway, good open floor plan design is a solved problem, all except for the fact that it hasn't photographed well since Gordon Bunshaft and SOM designed Lever House and CIGNA in the 50's and 60's.
Which is to say is that the problem with good open office design is that it doesn't look like photographs of office spaces in recent issues of magazines (aka "archiporn"). Instead it looks a lot like class "A" office space in a suburban office park - carpet, gypsum wall board, acoustic ceiling tile, and fabric covered modular office walls (aka "cubicles"). All these reduce sound transmission and reflection and impact noise - and if cubicle height is thoughtfully selected provide reasonable balance between visual communication and visual isolation and hopefully shared natural light. And if the holy grail of being able to select HVAC systems exists, then good white noise acoustic masking can be provided and that is even better than chasing sound attenuation.
Sharing the natural light means putting the private offices on the core and the serf farm by the windows. This of course means overcoming the sina qua non of hipsterism - status consciousness. But then again at the point where a leadership team has bought functional design over archiporn, this is just the last hurdle.
The problem of course is that corporate grade solutions require corporate grade budgets. Good systems furniture is more expensive than cheap doors, drywall and paint - as is good open plan office space versus lower quality space. On the flip side, acoustic ceiling tile and carpet are less than painted ductwork and stained concrete.
Anyway, the important change to architectural design over the past century is not an evolution of visual style. It's the increasingly sophisticated material options and the need to integrate an ever growing number of building service systems. The problem as always remains convincing lay people that living in a house isn't a good basis of experience for designing a workplace for others. The optimization problems are radically different.
Truly useful innovations in architectural design occur far less frequently than useful innovations in algorithms.