A sparking or blazing engine will be far easier to see if the lights are out, and hence no internal reflections. I recently flew from BKK to HKT on a TG AB6 and none of the lights were dimmed for either TO or landing. As well as the obvious safety hazard, there was also the ire arising from the fact that you cannot see the beautful Thai scenery when the cabin lights are set to MAX.
Upon querying this with the Purse on disembarkation, I was told that she simply "forgot" to dim the lights.
Hmmmm....................