Please educate me.
I'm not the expert, but it seems to me that all the data that's being transmitted by an "enhanced surveillance" mode S can be put into a computer straight away, and the computer will then calculate where the aircraft is going to be in a few minutes time, where everybody else is going to be in a few minutes time, and whether that's going to lead to any conflict.
That's an essential condition for "free flight" which essentially means that IFR flights can fly DCT from departure to destination instead of having to fly fixed routes. And that, in turn, may lead to significant savings in fuel and time. Plus it will allow more efficient use of airspace and better timings of arrivals so runway use can be optimized.
Of course you can derive some of the data by observing the radar track for a few minutes but that will be slower and doesn't take into account things like speed/heading/altitude changes. If you know what the FMS has been set to (including current and set airspeed, current and set heading, rate of turn, current and set altitude/fl, rate of climb or descent and current wind conditions) it's far easier to predict what the aircraft is going to do in a few minutes time. And that's essentially what EHS is about - uploading the most important FMS parameters to the radar controller.
I agree that a human cannot possibly comprehend all data that's being transmitted by 100s of mode-s transponders simultaneously. But a computer can.