As you will know Pascal's principle underpins all of this stuff - this is where Physics becomes interesting
Basically the lever pressure is primarily determined by the master cylinder piston /clutch cylinder piston diameter ratios.
A small diameter master piston combined with a large diameter slave will provide an easy pull. Unfortunately, that ratio
might also mean that the slave piston doesn't move much and so the plates might not dis-engage. Thus the ratio's and the
throw are "balanced" to provide a reasonable compromise.
I suspect that both the SD's master and slave were chosen on the basis of what was readily available and provided good value
for money. Certainly, the slave could have been much better engineered but was just readily available.
Given the build decisions it is not surprising that the Master and Slave are slightly mismatched resulting in what is considered
a hard pull. This could be fixed if you want to spend money but it is probably not worthwhile.
That's the physics but there is also a possibility that human factors have come into play. It is possible, for example, that
somebody has over-tightened the clutch springs, somebody has replaced the springs with the wrong sort - the "heavy duty" type,
that the fluid is wrong, that the clutch push-rod is bent, that you've had a stroke and the left side of your body is weak
(that's a right sided stroke) or any number of factors ... Compare with somebody else's SD not with other brands.
Good luck.