Open floor plans aren't really as universal as they seem - plenty of newer buildings still have offices and cubicles, so your company's choice might genuinely be their philosophy rather than what's objectively trendy. That said, the open layout was definitely pushed hard starting in the 2010s, and the reasoning came from a mix of things: real estate costs (you fit more people in less square footage), the belief that proximity breeds collaboration, and a general cultural shift toward casualness and transparency in workplaces.
The productivity question is where it gets messy. Research pretty consistently shows that open floors are great for some things - informal chats and quick problem-solving happen more naturally. But they're rough on focus work, and people report more stress and interruptions. So it really depends on what your company actually does. A startup that thrives on constant collaboration? Maybe it works. A team that needs deep concentration? It's probably making everyone miserable. The honest answer is that it was sold to a lot of companies as a universal fix when it's actually just a trade-off.
As for whether it's dying out - there's definitely been pushback since around 2020 or so. People got remote work, came back, and realized they'd forgotten how exhausting constant visibility is. Some companies are adding quiet zones, phone booths, and focus rooms back in. Others have doubled down on it. So it's not exactly fading away everywhere, but the "open floor plans are the future" cheerleading has definitely cooled down. Whether your employer is being budget-conscious or genuinely believes in it is something only they could tell you, though both things are probably true to some degree.