The latest is that it's lost some of its popularity because it hasn't proved to be as scientifically valuable as we once thought. There was a large study recently published from Harvard that failed to show a protective effect of a high-fiber diet in preventing bowel cancer. Some older research from the 50s and 60s showed that people with high-fiber diets were less likely to have a variety of bowel problems. Fiber definitely benefits bowel health and reduces constipation and diverticulitis. It's just uncertain about reducing cancer.
More definitive work needs to be done.
That's a good question. Caffeine is one of the most studied chemicals in food and to date, very little bad has been proven. It is a stimulant, so the extent to which people are made nervous by that effect, it has that adverse effect. But it does not appear to have any relationship to cancer or heart disease or high blood pressure or diabetes. The foods that go with coffee sometimes cause heart disease, like cream, sugar and pastries or donuts.