I'll never get the obsession Hollywood has now with using the actor's voice for singing when a substitute voice would work well and open up more opportunities. For every Anne Hathaway in Les Miserables or... Anne Hathaway in Les Miserables you get a Russel Crowe, Pierce Brosnan or Emma Watson.
...nah but seriously though Hollywood's lack of diversity has come to bite them in the ass. Watch them just CGI Aladdin and have Tom Hanks or someone voice.
Hell, they did this for Aladdin! I have no idea why they want the same person acting and singing. Who cares.