I agree, as an employee. I mentioned this to my director and he also agreed with me but brought up some logistics I hadn't thought about because it wasn't my job to care.
What do you do about office space? The company is paying a ton of money to give everyone their desks. How do you handle the logistics of having people coming in on random days? Share desks? What if you both come in on the same day? Have unassigned desks? So you're sitting by random people? But the point of coming in is being with your team. But how do you coordinate that? What if half your team chooses monday/tuesday for their office days and the other half chooses something else? None of these are show stoppers, but I also can list a bunch more little "paper-cut" problems with the hybrid approach at scale.
At some point it's just fully-remote with an expensive office. I think those things will naturally work themselves out. But it makes sense why someone who's job it is to care will not know up front to solve it. I think the solution is to not try and solve it ahead of time.
At some point it seems we'll naturally converge on smaller office spaces with more OFFICES and less "open". Some people will always want to come into the office. Those people will be supported. Some people will never want to come into the office. Those people will also be supported. Teams will figure out what works best for them.
For me, I plan to work fully remote the rest of my career. And right now that's a sword I'm willing to die on. Do I miss some things about in-office attendance? Yes! So I plan to go in occasionally. I'll plan that around the schedules of people I want/need to see. Also, sometimes I just need a freaking shared whiteboard. And no, Draw.Io and digital whiteboards somehow just don't work the way I want.