I was thinking about this the other day, and I thought of a few things that Dark Angels need to become a more characterful army. Their looks are second to none, but their rules don't exactly follow suit. Here's what I came up with:
Deathwing: The Deathwing are quite used to going up against insurmountable odds, it's what gave them their bone-white color scheme and that tradition still rings true. To reflect this, all Deathwing should be immune to the effects of the No Retreat! rule. They should also have to select an opponent's HQ at the beginning of the game, against that model and its unit they gain the Preferred Enemy USR as this HQ has information about the Fallen.
Ravenwing: All of them should have the Skilled Rider USR, and furthermore they should always get some kind of save, or have their normal save increased to reflect their skill at dodging incoming fire. Back in 3rd edition, they had a "jink" save that was always on a 6+.
Also, why bother giving Sammael a jetbike when no one else can take one? He should be able to take an Honor Guard, all of whom have jetbikes. The Dark Angels have access to many ancient pieces of equipment, why not more than one bike?
They should be able to take the Mortis Pattern Dreadnought.
They may not get a new codex for a while, maybe I should let my friend who plays Dark Angels to try out these rules and see if they are balanced.