[Ludwig]

If I play too fast equipment, I make more errors and loose more games. But rubbers that are to slow cut down on my ability to generate good attacking strokes. The same goes for spin: too spinny a rubber will lead to unforced errors against somebody able to put spin on the ball. A not spinny rubber can't generate spin to make life difficult for the opponent. It is much easier to play with an attacking no spin rubber like short pips against the long pips and anti players, too. If you don't put spin on the ball, they can't use that spin against you.
Every player has to find the right balance regarding spin and speed of his equipment compared to his ability.
Since I am not a very good player (Kreisklasse), I don't glue my rubbers before games, use only 1.8mm sponge but have a spinny chinese rubber, that can give me trouble playing somebody able to put changing spins on the ball.
My rubber of choice would be a hardbat (pips out without sponge) rubber for everybody. That would generate a more level playing field: nobody is able to force points using spin or speed, placement and variation are necessary and lead to longer rallies, giving more workout. The current rubbers used in tabletennis are too fast and too spinny, points are mostly short, the game has more breaks then playing time.