I'm not a singer, but sometimes it's more impressive to see someone show a range of styles and sing in a fashion that's appropriate to the occasion. I don 't think a classical opera voice would have worked there.
Another very impressive performance was Tony Bennett's farewell concert at Radio City Music Hall with his friend Lady Gaga. He is 95 and has advanced Alzheimer's to the point he can't sustain a conversation but as soon as he got onstage he switched on and for an hour gave a full throated performance that would have done proud to someone half his age. Lady Gaga said she met Bennett when he came up to after a charity performance and told her she was a jazz singer, which she never considered. It led to a 10 year collaboration and friendship.
Here's a link to a 60 minute piece about it:
Tony Bennett and Lady Gaga prepare for Bennett's last big concert