Personally, I don't think that resources are that huge of an issue. This game puts out a lot of stuff. I think that time management, prioritization and game-design are the issues. They, or others, may say how they are short staffed, but really, they are putting out a lot of content. Patch cycles are frequent, and they create whole new dungeons in addition to things like Diadem, LoV etc. The issue was, that LoV and Diadem sucked - and that was a lot of development time I am sure.
If I were a lead on this project, I'd focus priorities on 2 aspects - 1. what do and will most people take part in, and 2. what will have the most far reaching effects. I include 2., because I think that even though raiding is probably not enjoyed by the majority, it's effects are widespread to the entire community. In this case, I wouldn't focus so many efforts on things like LoV, as even at best that would very likely not be engaging for the majority of the playerbase. Instead, I'd have put a lot of resources into the relic. I'd do this because it would appear that the vast majority of players - casual and hardcore alike - take part in this activity. I'd want the relic to be the absolute best content addition to the game.