"I'm just wondering that why Divinity looks..."
Because Diablo is popular. The same thing happens with MS Office, etc. To expand on what LordMalis said, if there are a large number of people used to doing/seeing something a particular way, then that becomes the default 'intuitive' method. Programs in a similar category that try to do something too differently (even if it is 'better') risk support issues from people not being able figure something out, and poor reviews due to 'un-intuitive' controls. Sometimes the benefits outweigh the potential problems, but there are a limited number of ways to display menu buttons and health/mana status, with little practical difference between them. For the changes shown in the Beyond Divinity screenshots, there are many other games that have used health/mana bars beneath a character's icon.
"...and feels quite much like Diablo"
I didn't find that, except for much of the catacombs and wastelands. Even then, the mood was a little different.
