It would certainly have been a factor hence my versatility comment. Also with only one deck cat&trap doesn't give you any redundancy. At least you are not as dependent on ship speed, there are more landing spots if someone messes up, and ultimately probably a lot more emergency decks around. 'Over the side' was an expedient way of getting a clear deck when aircraft were cheap and plentiful.
I might also say that we have a history of major reconstruction through life so adding catobar and an angled deck would not be impossible in 20 years time.