can't you just set the new tab page url to the wikipedia random page link?

Actually not, the only way to do this is using an extension. The source code is here: https://github.com/tarla/random-wikipedia-chrome-extension

If my memory is right it was possible in old versions of Chrome.

I see it's possible in current Firefox, but only for new windows :/

Neat idea, but why exactly does it need to read my browsing history?

It doesn't! the real code is pretty much one line in the background.js here: https://github.com/tarla/random-wikipedia-chrome-extension

the other parts are just to add a donate button that redirects to Wikimedia Foundation page

That's from the "tabs" permission; I'm not sure why the extension requests it, as it doesn't appear that it's required by the code (the chrome.tabs API does not require it, you only need the permission if you're reading the URL/title/favicon of existing tabs AFAIK).

Since the sole feature of this extension is pretty trivial and can be easily replaced with a bookmark, I would be honestly worried about some "hidden features".

The barely two sentence description and low resolution preview picture also don't inspire much confidence.

actually the source code is here, it is basically one method to override the default new tab behaviour. https://github.com/tarla/random-wikipedia-chrome-extension

Oddly, the only way to change the new tab page is with an extension.

With Firefox, you can add a link to your new tab page (and everybody else's) just by paying Mozilla a hefty sum!

Your overview page appears to have two copies of the same image.

I'll fix that and add a pretty description, thanks!

That really looks like a lot of work, congratulations!