I like a bit of eye candy, but the external camera is too powerful and too easy to abuse for my liking. The event camera, on the other hand, doesn't give the player that much information. Also, a lot of the info that the EC does give - such as whether or not a torpedo missed, and even whether it missed aft of the target or not - could be determined by the hydrophone operator, I should think.
For those who agree with the above, the event camera can be enabled with no realism hit. For those who disagree, the event camera can be disabled. Seems like a win/win to me, which is why I put it in the mod.
In my current career I actually have the EC turned off, but it's nice to know I can turn it on any time.