LEDs are just a light source and needs optical components to keep light where you want it. If too much light is bleeding off in unwanted directions, more LEDs are needed, cost goes up, power consumption goes up, heat sink gets big and fabrication time increases. OEM normally uses a single parabolic reflector around each LED. This is cheap for them to make because of volume, but creating or reproducing them in the garage is not economically feasable. 5mm diameter LEDs comes with a built in lens that will narrow down the beam. A low angle beam LED can relativly easy be made into a wider angle by simply making shape of the cone flatter. An oval beam can also be made by shaving in one direction. A low powered hand sander with around 150 grit will do this easily. Be careful not to overheat LEDs.