In general, I think it's sad (and lazy). Older manuals were colourful, introduced to to the game and made you want to play it. Eventually most of them turned black and white and sounded very technical, like they were written by someone who never played the game before.
Now, many, if not most,are just the warnings, the license agreement, a controller-layout and maybe a link to a website were you can download the "full" manual.
I remember Fallout 2, that one was more a book than a manual, or Oblivion... every skill and spell explained. Heck, around here, some of the games like Secret of Mana came with a full walkthrough with loads of maps, screenshots and tables.
But need to accept it, the days of elaborate manuals are over in the modern age of fast information exchange through the internet. Cheaper and more convenient for the companies to put up a file somewhere.