More importantly, several of the studies only assessed dietary intake just once (at the beginning of the study), extrapolating for the remainder of time. Of course, these were prospective cohort, case-cohort, or nested case-control studies as it's impossible to perform a randomized, double-blind, placebo-controlled trial on the effects of dietary fiber.
However, as I've mentioned before, one should look for trends rather than flukes. In this situation, it's not easy to overlook over two dozen studies that have all arrived at essentially the same conclusion, that is that fiber is good for you. Of course, one then needs to get into the details of whether one kind of fiber is better than another. This meta-analysis points towards whole grains, not the commonly found & used refined kind. Refined grains are essentially devoid of germ & bran, which is where most of the good stuff is.
Some have argued that current day humans aren't meant to consume grains as our ancestors did not learn to cultivate agriculture until just recently. That may be so, but just because my great-great-great grandparents never saw an an airplane or experienced air conditioning doesn't mean that I need to avoid flying and swelter outdoors in the Las Vegas summer.