What I think needs to be done on SE's part is a full re-evaluation of what they visioned Diadem to be. I feel like they had no real direction with where they wanted it to go, and just tacked things onto it to try to make it appealing to more people then those who just do battle content.
I felt the nerf on 210 gear and the fast collection of the gear was coming, and I'm sort of glad, but at the same time, I feel like this has inadvertently destroyed diadem. People that have been doing it right along, will no longer do it since the ability to get rewards was nerfed. This is why I think they need to go back and look at what they wanted Diadem to be.