I don’t mind the back beadboard but it’s your choice and maybe you’re ready for a change. I think a great change could come from adding doors to the lower compartments-below the tv. Reduce the amount of items on the shelf and it will be fresh.

I think I would get some cardboard or something similar and cut it to fit the back of your bookcase and paint the cardboard the same color as your walls. That way, if you don't like it, you can take the painted cardboard/plywood out and go from there. I think it would look good if you were to put doors on the bottom three shelves on both sides. I think it would not be possible to put doors on the shelves under your TV. Then I would put fewer things on your shelves....and put 3 or 5 things (uneven number). You can put some books on but use some pretty bookends to hold them upright in the center or off to one side. I have some bookcases in my dining room I am thinking of doing the temporary back with removable cardboard painted....If you decide to do this, let me know.

I'd remove most of the small items, which are making the bookcase look a bit cluttered, and I'd add more books. I know the mantra is "one third books, one third objects, one third open space," but I like a bookcase that's more like two thirds books (admittedly, I do have a lot of books). The books may add all the color you need.

Bookcases should be mostly (90%) about books, in my view. Otherwise, they look like a cluttered gift shop, which is what this is starting to look like. Beyond that, I don’t see any reason to cover the bead board and in any event, the books will do that for you for the most part.