LEDs can do some excellent things, primarily generating a lot of photons for very little power input, with the opportunity to have a fine degree of control over the details. Optically, though, they need a little help.
Fortunately, for our undergraduate labs in need of an adjustable light source, a spherical glass lens and an adjustable housing collimate them well enough. Which, when you need to build a lab’s worth of these things, makes life in the basement a whole lot simpler.