TLDR: The content has not been deleted. Rather, it has been moved. And it was expected, as it has been standard procedure for when a new president has taken over in the digital age.

Why is this surprising? Of course a new administration is not going to leave policy oriented web pages from a previous one online.

Agreed. This seems to be true for many pages besides civil rights and climate change, such as education. [0]

0:https://www.whitehouse.gov/issues/education

The ones that seem to be flipping out about this have been the typical anti-Trump sources. Vox Media sites were some of the first I saw this on, and it spread from there.

This isn't really news, all of the old content was migrated to obamawhitehouse.gov, since that was the Obama administration's website.

Clickbait. Sad from Boston Globe to stoop to this level.

Get ready for more, it may be that the only way to neuter national discontent with Trump is with outrage fatigue.

Because the entire website was taken down and replaced with a new Trump White House website. This happens every time a new President takes over.

How is this news? This would have occurred even if Hillary Clinton or anyone else was elected president.

Because it makes for a good, sensationalist headline to pick a random page that used to be up and say "Trump removes page about <key topic>!" and all the people who just read headlines freak out and spread it around, everyone conveniently ignoring that the entire website was replaced, so of course old pages will be gone.