Building rockets and probes for a reasonable price and in a reasonable amount of time. SLS was initially billed as "a simple project to reuse a bunch of parts from the Space Shuttle" and yet it's over a decade old, 20 billions in cost and has not launched even once. So we get no real innovation (as I said previously it's just reusing fairly old technologies), it's not cheap and it's not fast. As for keeping the specialists hot; surely there are better ways to do it. It feels like saying let's keep digging ditches and filling them back up to keep our ditch diggers in shape.