This isn't so much a limited resource problem as an allocation problem. If US, and western, interest increases in science then funding more missions like these will be more popular and Congress will increase budgets. But budget allocations are low because they are unpopular. We talk about the high costs of these missions but they are close to rounding errors in the US yearly budget. It's weird to me that we argue over pennies when we're spending hundreds with no question. We'd say that's insane if we were trying to set budgets for ourselves. The reason it works it because the total numbers are large and we aren't scaling properly. It's a distraction.