The Japanese love hidden messages about hope, love, kindheartedness, etc. so during the translation, this was also translated. There are tons of stuff like this in all of the games, and I had a difficult time understanding what they intended to say with "Those whose memories fade seek to carve them in their hearts" and I think still don't fully understand it. Maybe it doesn't mean anything special, or maybe they spent days thinking up a statement like that.
The Cinnabar Mansion diary entries aren't as meaningful (or is that meaningless?) as the notice-boards on the locked islands, since they talk about events seen in Pokemon the First Movie (the discovery of Mew, Mewtwo's creation) and the huge hole in the building seems to be the part that Mewtwo destroyed after escaping. (Only in the game, Mewtwo is not captured by Giovanni.)
So, these signs might serve no purpose apart from stashing "moral messages" into your brain, at a semi-conscious level. Messages like this are all over the place, but the best example are the boards at the island where Lati@s is caught. For example, you might not catch certain messages about "loving your Pokemon" specifically, but you're sure you've seen them all over the place. "No use loving your Pokemon", you might say "they don't exist", but there are certain similarities between Pokemon and animals. After all, the creator of Pokemon ( that is, Pocket Monsters) was inspired by bugs at his local pond.
But after all I've said, the fact remains that I can't visit these islands due to a "Nintendo joke" (and that's what it is if you think about it) and it makes me mad. I wonder what insipid Japanese event-removal NoA will think up for D/P. Humph.
