Perhaps it depends on exactly how well you read the reports. When I read the reports I *never* got the idea that they were recommending refined flours, sugar, or other similar sources of sugar or starch. The closest I can come is a recommendation for baked potatoes...which is still sort of valid, though now we (or at least I) worry more about the starch.
Cholesterol is an interesting example, though. Lots of "experts" believed that cholesterol was a very bad thing, despite the fact that the myelin sheathes around the myleinated nerves require it to insulate the nerves. Also despite the fact that it's disassembled during digestion, and that the body makes its own cholesterol from available ingredients, even if there is none in your diet. And the evidence against it in the diet was always quite shaky. That's a real example of the "experts" being stampeded by a unreliable study.
The actual dietary recommendations haven't changed as much as the public image of them, but the "food pyramid" is by PR people. Some of them are also dietitians, but they're mainly political or marketing. So you need to read a bit carefully, because while the "best available recommendations" are available, they aren't always obvious. But lots of starch was NEVER among the "best available recommendations", and *I* didn't even read the old food pyramid that way. I read it as recommending lots of whole grains, but that's a lot different from corn starch and sugar.