I think (just thoughts here) that the idea would be to get the space needs out from under a single branch of the military. The Navy has had its own space program and needs for decades, the Air Force has its programs, and even the Army and Marines have user requirements for space. By getting that out from under the Air Force, it removes any bias (lot of that going round lately) in the allocation of funds for programs. I think a new 'space force' (hate that name) would consolidate the needs of all the services and the other agencies who have requirements for space assets. In that sense, it seems like a good idea.
Don't envision this as 'Buck Rogers'. Its much less about that and more about making sure that services like GPS, space surveillance, and other needs are met without having a single service arbitrating between the cost of sustaining GPS and the cost of the next strategic bomber or nuclear submarine force, for example.
Took the words right outta my mouth!