Immortal25,
your post was filled with meaningful questions, though all of them rhetorical. Seems to me you are looking for confirmation of your own thoughts and ideas , well ,fine, I agree with you.
Crunches are a fine way to increase core strength, safe, relatively easy and simple to learn. Done with hips and knees bent , will reliably improve the holding power of the front of your back,( so to speak ). The real trouble lies not with wether this or that exercise is better or not ( a bit like polishing apples, they don't taste any better no matter how shiny ), but with the more difficult area of compliance.
Ergo, K.I.S.S. works better than any length to which the energetic exercise zealot could go to achieve better or similar results. The more difficult the exercise , the less it will be done.