I think they should follow Navy convention. A space force is more like a navy than it is like an air force. A navy, unlike other military forces, is based and operates in a vast hostile natural environment in which exposed humans cannot live or operate, which therefore requires its personnel to be based on (not merely operate in) enclosed protective mobile bases, called ships. In particular, a space force is like the submarine service; the biggest difference is that the pressure hull keeps pressure in, rather than out.
As for the need for a space force--necessity will rule. We need to be prepared for the necessity, but not contribute to creating it.