DK TANK spec and AOE

Hey there everyone.

So I'm beginning to get close to hitting level 80 on my DK. I will be aiming to tank but I have some questions regarding spec and aoe threat..
About 4 years ago I rolled a frost tank on icecrown and I really did enjoy it alot, I also had great aoe threat compared to blood.. What I want to know is why is everyone rolling blood? I get it has great self healing but to me it seems its aoe is terrible?

So what I want to know is frost still viable for endgame dungeons and raids? I found it a lot of fun. If the answer to that is a no then can someone explain what talents are worth digging into in order to be able to hold aoe threat in blood please =)

Fanks

Blood has terrible aggro in aoe, icc rs and toc have no need for aoe aggro and blood is better in other aspects, frost is still viable endgame but the later u go the worst it gets which is complete oposite of blood.