I don't even understand why do the other Forces even exist. The Speed Force is practical enough on its own.

Honestly agree. Still Force is the only one I can kinda see since it's a ying yang deal of the Speed Force by being it's opposite of lack of motion. So there's intrigue there. The rest have very redundant effects.

If the Negative Speed Force is exposed to the Speed Force, then it starts to kill the Speed Force, and the Negative Speed Force can time travel without a cosmic treadmill and can alter their own age, including more. It's literally a better version of the Speed Force. Also Zoom's powers is to control the time flow, you could freeze time, isn't that powerful?

For myself, who is late 90% of the time, I could DEFINITELY use some Speed Force.