[rcxdude]

I think the issue is that it isn't really taught: in science class and in popular science it's often mentioned that you should be on the lookout for small sample sizes in studies as a measure of quality, but it doesn't really go into much more detail than that. And in my mathematics education I wasn't taught about this effect until university (despite doing a lot of stats exercises involving sampling). And sample size is pretty much always an easy thing to pull out of a paper without much familiarity with the subject of the paper, while sample bias (a much bigger issue) can be much harder to address (though at least some people seem to be getting the idea that if you are sampling from university students like many papers do it's not exactly representitive of the general population).