The locking behind a raid is dumb yes, But still if you want it, Go work for it. a snippet from a blizzard post about it
This is not something you, by any means, "need". And "needing" it on every alt, doubly so. If you desire it, then organize a raid or join a guild that will put you in their raiding ranks and dedicate the time to obtaining the items.
We simply disagree that these skins should be handed out without dedication and challenge.