At risk of doing this to death...
Why not fix the problem of jackstall by inceasing the pump output (and possibly having to upgrade the whole system and redesign the airframe to cope with the consequential increased feedback forces, adding weight and reducing the useful load of the aircraft)?
Firstly, because jackstall occurs outside the normal flight regime and it requires high power, high speed and harsh manoeuvre to induce it. For example, we used to demo it to basic students in the military Gazelle AS341 by diving the aircraft at high power then pulling hard through the heavy vibration until a jack stalled. It was very unnatural to do it, we didn't like doing it because it felt awful to the airframe and I believe it was later removed from the syllabus. (It also scared the $hit out of most students).
The parameters required to induce jackstall will sound familiar to any helicopter pilot because they are also exactly those required to induce retreating blade stall.
There is little point modifying an aircraft already in safe and satisfactory service to prevent jackstall if retreating blade stall will subsequently occur at only a slightly higher speed, power, or manoeuvre limit.
Secondly, market forces rule. It's a fact. Any aircraft can be redesigned (at a cost) to perform better but we aren't talking about an agile fighter here, it's a small helicopter for goodness sake! Who would pay? The manufacturer, or the customer, especially if there is nil perceived benefit?
Finally, jackstall tends to result in the aircraft throwing off pitch so that it is a short-lived phenomena, unlike retreating blade stall. As I said earlier, I would rather suffer jackstall than get RBS a few knots later. The aircraft limitations are there for a reason. Observing them is what we get paid for.