2.) You can put magic find, gold find, and now item multiplication!? and affix those skills to runes and skills in general instead of just items.
3.) You don't have to restrict content like rings to make them seem more awesome, you just have to make more cool stuff in general.
4.) You could give flasks neat magical properties and refill them slowly by killing monsters instead of weird red blobs all over the place.
5.) People really do love options and customization, and it is possible to make a game that allows for dual fist weapon wielding spellcasters and magic casting tanks. Hell, how about anybody can cast anything?
6.) Remember how cool it was in Diablo 2 to turn a regular nice item into an awesome rare once in the lifetime of the character? Why not be able to do that more often and with an item you have access to carry/store?
7.) Pets are silly.
8.) So is Diablo 3's cartoon art.