In TT everything’s relative to your level. Your preference is also by definition not an objective.
Often softer rubbers are used at the stage where you’re still seeking to develop your technique. To get a feel for the ball, the contact at impact. As people proceed, they might start to seek a higher pressure envelope.
Everything’s relative, everythings a tradeoff. Given an equally frictive surface, it will be easier to transfer power (both in velocity and rotation) to the ball, more relative yield in low impact strokes. (Which has its downsides, as well: more bouncy and spin-sensitive in passive play.
Harder rubbers are more demanding, less forgiving in ball contact and timing. The reward is a higher upper output limit.