Seen through the most charitable glasses, the purpose of Soace Force is that any major-power shooting war is now likely to involve rapid space-based asset degradation.

Fighting such a war without a unified command over the theater in which that action unfolds seems destined for failure.

And failure to preserve or triumph in space substantially degrades planetary military capabilities.

So really, Space Force is an expression of "space is important to all the other military things we do now."