I know this has been mentioned a hundred times, and I get the feeling it's not going to happen for some unforeseen reason Blizzard isn't telling us. Agree? Which is why I'd like to know why? The first thing I think of is maybe it's a technical hurdle to make it work, but with how much cross server technology and systems already in place it seems like making account-wide ignore would be an easy task to accomplish.
Another reason might be because of priorities. This being a core improvement to the game however seems like it would be a high priority right behind server merges and new patch content, so it still doesn't make sense why it's not in the game yet. Then again we all know Blizzard has been very reluctant to begin server merges, but why the same attitude towards account-ignore? What is it they don't want us to know?
Is it because they think if someone gets ignored too much they'll stop playing?