1Mb block limit is not on the WP but Satoshi himself put it.
Discussion
That was supposed to be temporary too
it was, either way, it's not on the WP, Satoshi put the limit there and didn't even mention it to anyone, but he felt he had to do it at the time. The WP only describes how the network works, POW, issuance, difficulty adjustment etc. Many implementation details were determined later.