4 people making the job are faster than 1 person making the same job.
Also, 4 cores can process 4 AIs or 4 physics bodies, or something else at the same time.
You can apply multi-threading in all kind of computations.
I repeat, 4 people makes a job faster than 1 person, so you can use threading to make more computations at the same time, so 4 times faster!
And this is important for complex games. Games that may use difficult and long IK computations, or massive physics or movement in general.
Also we are now on multicore era, and this would be an important feature.
p.s.: also you can check 4 events at a time instead of just 1.. Something like a block of events