It seems that whenever something or someone goes haywire, fails or is about to explode, light is going to flash rapidly, randomly and brightly, whether it originates from buttons, lamps, screens or even eyes and orifices. Justified in failing lightbulbs and warning lamps, but may otherwise lead to moments of failed awesomeness.
Notable offenders are the (more contemporary) horror and science fiction genres. Somehow many film and video game-makers believe Everything Is Better with Flashing even though it's not always that awesome. Older video games often employed flashing screen effects because color-cycling demands so little processing power; since advances in graphics technology have discredited this excuse, toning down flashing lights or patterns that could trigger seizures has become one of the few alterations routinely made to classic games in official emulated rereleases such as on the Virtual Console.
Not in any way related to Epileptic Trees. Compare to Power Glows, where light produces a positive effect, and Glowing Eyes of Doom, which implies imminent evil rather than imminent (self)destruction. See also Brown Note, Red Alert, Technicolor Death, Stop Motion Lighting, Blinding Camera Flash, and Throat Light. May fall under Sensory Abuse. Subtrope of Sensory Overload.
Truth in Television, but only for people with very severe ("photosensitive") epilepsy. Most people with epilepsy can look at flashing lights with impunity and only have to watch out for things that physically affect their brain chemistry (acute stress, alcohol/drugs, sleep deprivation, etc).