Well on top of the legendary cloak, we also have a meta gem. That's 2 procs we pretty much have going INTO siege. This isn't Dragon Soul where they basically needed to give us a weapon with a proc to compete with the casters who had the Tarecgosa staff or rogues with their daggers. Also in Wrath, you had to get exalted inside ICC for the ring with it's proc; and if you were a plate dps- you'd have to farm ICC for months and kill LK multiple times for that legendary to get your second proc, and you'd only get to use for 2-3 months. At least the cloak, though it's not as prestigious as other legendaries before it, will be obtained within the first week of 5.4 and we will have it's benefit throughout all of Siege and into the next expansion.
So hey just be happy with what we have and rejoice over the fact we will have a chance at some of the BEST leveling heirlooms off Garrosh.