The nature of Cassini's mission is much different than planetary exploration on the ground. A better comparison would be the rovers on Mars vs a manned mission. Bad news is that our best rovers are incredibly inefficient.
A better comparison, yes.
Rovers are quite efficient when one looks at relative cost & risk.
One manned mission would cost far far more than 2 rovers.
If the former fails, it breaks all the eggs in one basket.
But if one rover fails, there's a back-up.
And even a replacement mission is relatively cheap.
(Caution: We must ensure there's no V'ger scenario.)
Add to all this that advances in AI will make unmanned probes
increasingly capable. But humans aren't undergoing any improvements.
The nature of space exploration will change because of this.
We must avoid being seduced by Star Trekkian notions of
easy, safe, comfortable, cost-conscious-free space tourism.
But if Mars is the goal, I agree that lengthy experience on a Moon
base should be the baby step.