One of the fundamentals every manager needs to learn is, people are not all like you. Extroverts may need someone to bounce ideas off of. Introverts may need a time to bring something they have been thinking about to your attention, because otherwise they assume you don't want to be bothered.
People have families and relationships and health issues outside of work that never the less it may be helpful to discuss if it impacts stress, times they can be in the office, their work flow, etc.
And then, and this is truly important, there are interpersonal relationships in the office. Are two employees not getting along? Having a 1:1 with them will often let you get both sides of the story, instead of, potentially, hearing nothing about it.
Finally, while your bosses may have been fine with you discussing something with them any time you wanted, or fine with an email on a topic, I personally hate being interrupted, and would prefer anything like that be scheduled, and find that in person or video chat conversations are helpful in providing context that text communications, especially those that aren't in real time and interactive, may lack.