Googling around I found three books explaining to some degree the difference between 'Point-and-click' and what they call 'Direct-Control'.
Book: Game Design Secrets
Book: Fundamentals of Game Design
Book: Andrew Rollings and Ernest Adams on Game Design
Although they state that Point-and-click has been the standard for years in adventure-games, action oriented games demanded a more direct form of control. Hence keyboard control. As Andrew Rolling and Ernest Adams point out:
In a direct control user interface, the player’s commands say “Walk in this direction” rather than “Walk to this point”
A valid point in the book Game Design Secrets about Facebook games is that point-and-click works better in that specific context because:
This is in line with the facebook UI itself, which emphasizes mouse-based interaction as much as possible, and the preferences of most Facebook gamers, who are casual, light gamers accustomed to simple gameplay interaction
It seems that direct keyboard control works better in fast-paced games where skill is involved.
Combining keyboard and mouse also gives the added benefit of extra control and keys. PC-games where the character is able to jump, run, duck, swim, move, speak, reload, etc. demand a lot of control from the user. Having a mouse alone doesn't provide the keys needed to bind all actions to, and in that context, point-and-click will give massive usability issues since putting all those actions on the screen requires a lot of ui elements, complex functionality and precious screen space.
What you are going to implement is really up to your goal and context. What platform is it for, what's the skill of your general player base, will they be playing on a tablet as well?
Hope this helps you further.