I am perplexed.
The crisp butter vs. soft shortening.
My grandma made her cookies with shortening.
In my hedonist gourmet adult world, I made cookies with butter.
They were never the same.
This year, I made a batch of chocolate chip cookies using Grandma's shortening. They were dead on (except for Nestle's changing the recipe on the chocolate chips), and they were thin, crisp, and exactly as I remembered.
My experience is that butter is soft and chewy and shortening is crisp. The element that was missing from my chocolate chip cookies that I missed from my grandmother's cookies.