Ubisoft is digging themselves a hole that they most likely will not get out of. With DRM and now the lack of game manuals, I doubt they'll even last 3 years.
On another note, I rather like having a physical copy (read: paper) of the manual. I like reading the manual before I get the game installed (for example, as soon as I purchase a game). And then there's the fact that I may want to read the manual when I'm playing the game. I can't read a PDF while I'm playing a game, unless things have drastically changed (no, I should not have to purchase a 2nd monitor).
And then there are games like Grand Theft Auto that include large colorful poster/maps of the in game world. Whenever I play a GTA game, I usually post the map above my computer as a reference. That's a reason why I've never purchased a GTA game (I don't even know if the digital versions include the map as a PDF file) through digital distribution (eg: Steam). For one, my printer can not print pages that large. Secondly, since I would have to print a rather large and colorful page, it would eat through my ink. And then there's the fact that (for an example) the GTA games are cheaper at retail than on Steam. I can (and did get) GTA4 for $20 several months ago, while on Steam it's still $30. I got the older games years ago, but today III, Vice City and San Andreas can all be had for $10 each.