I've been WFM for 7 years now. I don't think RTO is a bad thing, but its all situational. How silo'd are projects and how much inter-team coordination do you need? How long is your commute? What kind of person are you (some people just work better in office environments)? Do you need physical access to equipment? The list goes on.
Being fully remote has allowed flexibility for team members to relocate without being forced to leave and thats been the biggest advantage. Going from a FTO to WFO or RTO is a big transition that requires re-defining workflows and communication mechanisms. Products like Zoom and Slack have made that far easier, but the bigger the organization, the harder the transition.
Personally, I miss having an office. I've lost human connection by being isolated at home that isn't replaced with normal social interactions. Maybe thats just older men not making time, but office space traditionally filled that role for me.