Sending any spacecraft to that system would be an enormous effort. And extremely expensive. There are many other missions crying out for funding, many other worthy projects to be attempted in places where we have never been. To send a spacecraft to Europa with just the (very high risk) mission to explore its ocean would be like saving up for a lifetime to go to Paris and then just having lunch at the airport and coming straight home.

Granted, a very small chance exists we might strike colossal scientific paydirt, but the chances are we probably just find, at best, brine. That kind of of effort and expense can only be justified by a mission that maximizes the total scientific payoff by having multiple targets and backups, and alternative Plans B, C, D,... etc.

The very nature of these deep space missions demands that we get good scientific returns even if there are multiple system failures on the spacecraft. A soft landing on an outer planet satellite, perhaps with a rover, then piercing the ice to release a probe into an ocean that may or may not even be there is asking a lot. Too many points of failure, and even if we succeed there may be nothing there to show for it.