It’s not surprising that it is online again. For one, it is still hard to predict infection rates so far out and a new variant could pop up.
Regardless of Covid, Apple has found that it is less stressful on their teams who had to take time off to prepare and attend the events. Developers seem to like the virtual Q&A sessions as they are easier to manage and much less costly than trying to travel to the Bay Area and stay for several days.
I see that they are hosting a smaller live event with press and students and that seems more manageable. That may be a model for a hybrid event in coming years.