In bodybuilding the benefits of long muscle bellies are fairly self evident, just look at Ronnie Coleman's out of place biceps and compare them to Sergio Oliva. For any sport requiring strength there would also be significant benefits simply due to the increased muscle mass. In the case of the legs, there seems to be a fair amount of literature showing that long achilles tendons and short calf muscle bellies are an ideal combination for runners, so there's an obvious reason why someone would have long tendons and short muscles in the lower extremeties. I can even make a hypothesis that not having a too long bicep and having a longer tendond distally would allow for better elbow ROM, but for the forearm, I haven't been able to find any literature, nor think of any practical benefit to having a short muscle belly and long tendons, yet some people have exactly that - a large flare right below the elbow with not much of a taper to the wrist.
I believe shorter muscle bellies fatigue faster and have greater explosive potential.
To get a full contraction on a short muscle belly, actin and myosin filaments have to attach, detatch, and reattach fewer times hence my belief that it would have greater explosive potential.