The spider makes a heavy hit!

With this attack you can see that the spider took a lot of the players health. The health glow is very small.
You can see in the flash animation, but not in this .GIF that when the spider makes a hit your screan flashes. You will always know when you were damaged. With the 'glow' health display, it's possible for an enemy to do a very miniscule amount of damage and perhaps you miss the change. However, with the screen flash it's obvious.