The solution to so many space logistics problems is: use a bigger rocket. Propellant depots allow you to add another solution: use more rockets.
Now, for some reason, many people who are advocates of propellant depots object to just using existing space storable propellants because that would mean you'd need to launch more mass than if you used cryogenic propellants. Well, so what? More launches - that's a good thing!
We don't need technology development to make propellant depots work. They already work.. we already have one in orbit!
Suppose you want to send 100 tons to Mars transfer orbit. You need either 236 tons of storable propellant or 144 tons of cryogenic propellant (and that's being overly generous to cryogenics). Instead of 5 Falcon Heavy launches you now only need 3. So what? How much is that worth?
So, ya know, NASA has selected companies to study storing cryogenic propellants in space.. and that's great. Technology development, in general, is fantastic and it makes things better in the future. Unfortunately I'm already hearing people say "woohoo! Now we'll have propellant depots and we won't have to waste $38 billion on a heavy lift vehicle to no-where!". Well, no. We already have propellant depots and we already don't need heavy lift to go beyond LEO.
There is, however, a few things that we are in desperate need of.... the political will to go, anywhere, on the government side, and an outspoken willingness to go it alone, if necessary, on the commercial side.