Conceding that it was a technical necessity, the replacement of live actors for in-game CGI rendered characters feels off in the Riven remake to me. Necessary because now you can walk all the way around them, the game can't assume a single viewing angle for videos to play out. Nor would it be practical to record new actors playing the roles (the old assets must surely be too low-quality to pass in a modern game, even if they go back to the source).
Part of Myst and Riven's charm in the 1990s was the immersion it offered, the world felt real, and the actors playing out characters added to it. The original point-and-click format feels dated today, but at the time, it was convincing enough to be believable.