#4 Reduces the number of bumps Bryan has to take in the ring
I remember being part of a teleconference with Impact Wrestling legend James Storm not long ago. He was asked by one of the journalists on the call what the difference between singles and tag team wrestling was. I still remember how he replied by saying that in tag team wrestling, you reduce the number of bumps you take by half.
It is quite a well known fact that Daniel Bryan has suffered a lot of wear and tear over the years. But in a tag team environment, the good thing is that it may be a lot less taxing for the former WWE Champion. By doing this, WWE is essentially reducing the risk of him suffering yet another concussion in the squared circle.
Daniel Bryan is a family man and his health is of paramount importance right now. This is the safer route.