It was a complicated mission profile
- they had very limited battery life and a very limited window to transmit to Cassini (Cassini could only hold so much data before it has to turn and transmit to earth).
- they had to get through the atmosphere quickly to do the ground measurements.
- they had to land at a much slower speed, than the speed it traveled through most of the atmosphere.
- they had a much denser atmosphere to negotiate, than at Mars.
- they had many more kilometers of effective atmosphere to travel through, than at Mars.