>>511150509I know it makes no sense to you; but that's how it always happens. History (at least history books) favor the new over the old. So, if you picked up an encyclopedia from 1922 (which I have before), you'd see a lot of information about the Woodrow Wilson presidency; and those pages came at the expense of some information (who knows, maybe the Polk administration).
For every year that passes, there is a mountain of 'new' things to talk about, so the older things are talked about less. Meanwhile; at a certain point, topics above a certain age get summarized; where most of the real history is dropped, and replaced with a few paragraphs which cover the basic appoints that most agree are important, and nothing else.
For example... If I were to ask you to name 2 policies of the William Henry Harrison administration, you probably couldn't; though I'm pretty sure that you WOULD be able to remember that he was the guy who only served 30 days before dying. So... nearly all of the major issues of the 1840's are forgotten, in exchange for one or two easy to remember bullet points.
As it applies to Obama, 200 years from no one will will know (or care about) any of his policies, successes or failures. Instead, his ENTIRE section will be about his being the first black president; and how that fit in to the larger arc of civil rights in the country.
It's the same with George Washington; where entire years of his administration get ignore in favor of the 'first president' discussion