A dome light radiates indirect light at various angles due to the LEDs being mounted at the surface and shinning up into the dome. When standard lighting is used direct reflection from the part can result in a hot spot (halation) causing inspection and reliability problems. As the dome light diffuses at all angles a target with a complicated shape can be uniformly lit with diffuse light from all angles eliminating hot spots. As the target is uniformly lit a stable reliable inspection can be easily setup.
To better understand the use of dome lights in the industry, you can see the following video to distinguish text on glossy surfaces.