I have mentioned on more than one occasion( I tend to be a broken record....... sorry) that the core is SO MUCH more that just the six pack muscles.
Although a six pack/slim mid section looks great, how the core performs functions in our everyday life is much more important. Because if it is not bad things can happen.
I have a confession. I have never had a six pack. When I first started exercising, I had no idea about "the core". That is your six pack right? I did those silly floor crunches just like everyone else and I wondered why I wasn't getting results. But, we know better now right?