one word:
advertising.
I think there was expectations that it might add to battery shift life, but when you consider that a battery is not a capacitor and does not -instantly- take back into it what it took out to make the truck move, you recognize that there is no way that you gain back all the energy.
What effect it does have is to take some of the kinetic energy from the truck's motion and instead of wasting it to external heat via friction in the brakes, it 'sinks' the energy back into the battery, but that energy does not completely turn back into the chemical energy that the battery can use, a good deal of it still winds up as heat, (and some is wasted as loss in the conversion of energy from kinetic to electric to chemical) but the battery is such a larger heat sink that it is less noticeable than if that same heat was all in the brake drum.

then whats the sense?

and if you wanted, it is possible to set up most ev100 trucks like that too, In my opinion, it's just that regen was so new, most customers wanted it to be just like an IC car, with plenty of coast, and since all their other electric forklifts coasted, we always set it up for what the customer wanted.
Regen does not add jack snot to the battery shift life, all it really does is extend the life of the brake shoes.

I have driven machines w/ regen (newer trucks) and when releasing the accel., its almost like appyling brakes.

not really, there is a click of the contactor and a bit of drag, but it depends on how it is setup when that clcik and drag happen (might be related to the accelerator pedal position and truck speed (so it regens when coasting), or it might be set to be related to the brake pedal switch so you actually have to touch the brake pedal to get regen.

thank you Ed, I'll look. Does it drive any different?

on ev100 trucks with regen, there is an added contactor that has it's own (large pigtail-stud type, with the stud being the cathode, so it is what we sometimes used to joke it is not a diode,it is a 'queerode', since the tail is the Anode) diode and heat-sink and current sensor.