I suppose you're right that it has to do with "giving the enemy a chance" (remember the old quote about how "no nation would use a submarine even if it could be made to work by some miracle"
*?), and I think it goes for other types of action, too.
And though the aversion to use submarines may seem unsound today, if it was considered a "no-no" back then, I don't blame them. It's slightly similar to the
Cluster Bomb debate today - yes, they may be hugely effective, but they kill lots of civilians even after the conflict, and it's not exactly "fair" to the enemy to release them from the high altitudes they drop them from. I suppose the Royal Navy in the 40's Britain might have felt the same way about submarines?
What's "fair" in war is an ongoing debate even today. Are cluster bombs OK? Land mines? Torture? Chemical Weapons? White Phosphorous? Bombing of hospitals occupied by hostile Army units? All
may (note emphasis) give you an advantage, but they are all controversial and under heavy debate.
*Not verbatim.