The reason behind that is that aggressive airdrops are hazardous. Entities might hit world object and die or can be shot down before they land die
You don't have to drop them on top of the enemy. There are usually enough places to drop them safely, even behind enemy lines. And as opposed to Paratroopers, they can hide after their drop because of their camo.
Falls are already compensated for having 4 men by having a very tight drop pattern compared to Paratroopers. You can drop them anywhere that's not right next to a building or a big hedge.