This might be one of those questions where you get as many reasons as you do people who answer.
I think landarc said it best.. there are many "traditions" recipes and what not that we all follow for one reason or another.. The best thing is getting to try a bunch of different ways and deciding which one you like best.
Having said that... I don't always use a mop.. when I do I use vinegar quite a bit. Mixed with apple juice maybe... sometimes beer, whatever I'm in the mood for. There is definitely room for debate and discussion.. I just like the taste it brings.
Let us know what you come up with in your trials