It is like red-flash from classic Doom. Take a direct hit by a rocket for 100+ damage and (if you survive) you are blinded and cannot see for a few seconds, more than enough time for the Cyberdemon to finish you off with another rocket (if you are in a level with plenty of walls like e2m8) because you cannot see where you are going.
Starsector does not need to recreate this effect so well (with white instead of red). The main thing that bothers me about the white flash is AI is not blinded like the player is (and AI can fight while player cannot see what is going on), although white flash in a dark room is annoying.