I've always meant to google Keith David, but I've never gotten around to it. I have no idea who he is, and was never even certain (until right now, I guess) he wasn't just a fictional celebrity like Nyte Blade.I think another part of it is that Keanu is a big star, and he features in movies that gamers will typically enjoy. (John Wick series, Matrix series, etc) Thus, in an era where game devs are increasingly trying to insert celebrities into their games, this big geek-friendly superstar will make bigger waves than other actors.
Other examples of movie stars having their voices and likenesses in games that I can think of include Burt Reynolds, Keith David, and Roddy Piper in Saints Row, Kevin Spacey in Call of Duty, Jean Reno and Takeshi Kaneshiro in Onimusha, etc. But none of these people have the star power of Keanu Reeves.