Texture, Not Taste, is the issue. From a reader:
As is being widely reported in articles on trans fats, the advantage they provide in cooking is not taste but texture. The crystalline structure of trans fats (similar to that found naturally in lard) make pastries flakier and fried foods crisper. The NYT has a particularly interesting article posted today http://www.nytimes.com/2006/12/11/nyregion/11fat.html describing a chef’s test of various oils and fats in preparation of tart pastry, french fries, and fried chicken. The verdict—Crisco, with trans fats, produced the best textured, but not necessarily tastiest, pasty and potatoes, but all fats produced a good fried chicken.