Having thrown reproduction stick nades weighted to weigh the same as a real German stick nade, I can say that the range they have ingame is, if anything, too little. The stick design was specifically used to give it an incredible range over the egg style nades. This is due, essentially, to different tactically doctrine. The Germans, starting WW1, saw grenades as offensive weapons. Thus they have little shrapnel, large explosive potential, and can be thrown quite far. Egg grenades are of a defensive type, that is, its hard to throw them far enough that you'll be out of danger. Thus, they usually have a small charge with lots of metal and shrapnel potential, and are meant to be thrown from a position of cover (thus a 'defensive' grenade).
Also, ingame, that's about 40 yards you're throwing the stick nade, not 100. You aren't a very good judge of distance dude.
On the use of grenades, grenades were used almost more than rifles in the attack, especially by the Germans. Stosstrupp in WW1, and pionier/FJ-pionier in WW2, had "waterwings", which were hung over their necks that were filled with grenades. In german doctrine at least, the weapons that won the battle for the infantry were the grenade and the machine gun. Rifles were only self defense weapons.
So essentially, the tons of grenade spam ingame is 100% correct. The throw distance on the egg grenades is correct. And the stick nades, if anything, should be thrown farther, and for the non-shrapnel ones, should have a much smaller cone of damage (german soldiers in WW1 would literally jump feet first into the blast to avoid concussive effects of it), and a much higher concussive blast, that should, if it doesn't kill, cause bleeding or extreme suppression.
The German Stormtrooper made expert use of the grenade from 1916-1918. Stormtrooper units were led in the attack by grenade throwers. These were the men with the strongest arms and greatest accuracy. In a battle within the trenches the grenade men would throw single or grouped grenades over or around corners. Following the explosions several men armed with the K98 short barrel carbines, pistols, bayonets, and sharpened shovels to finish of dazed defenders. The remaining members of the unit, in addition to carrying their own weapons, wore sandbags filled with grenades. Ernst Jünger recorded how he and other Stormtroopers would keep percussion grenades on one side and pull-cords on the other. During the attack Stormtroopers would pass grenades to the throwers at the front, with men replacing the throwers as they tried or were wounded, relentlessly pushing the attack forward.
While yes, this is on WW1, it was really little different in WW2, the same tactics applied. The germans simply loved the grenade.