They based the characters on those people. Of course they will look like them.
And even more in the case of DmC which was done in the Avatar film studio thing. If you saw the movie Avatar, you'll know what I'm talking about when I say that those computerized people really looked like their actors counterparts.
Also, Tameen said that they worked with a technology that takes the acting all at once. So voice, expression, and movements all at once. So they don't voice over some acting that they had previously done and sound not so convincing.