Blizzard appears to be trying to get different classes to explore varying archetypes, but to do so in their own way that does not merely replicate how others have done it in the past. All hints are that Blizzard experimenting with a controlling archetype for Rogue, and have been steadily giving the class the tools to succeed.
Rogue has always been tempo driven with limited healing or defensive options. With the Blade Flurry nerf it became nearly incapable of AoE as well. This made it a poor choice for the classic control style, because in order for such an approach to work one needs to be able to absorb a few hits then clear multiple threats with a single spell. Rogue could not afford the health, and lacked the card efficiency, simple as that. And if one's deck is nothing but removal to match the number of incoming threats aggressive decks can field, then it's an auto-loss to control or combo.
This last problem has been cautiously addressed, piece by piece, these last few expansions, primarily through their legendary cards. They tried first with Anub'arak but it was simply too clunky; afraid of Rogues being able to leverage both tempo and value, they opted for a card so low on tempo that it only found value against the slowest of the slow Tank Up! warriors. Since then there have been a few different experiments:
Sherazin, Corpse Flower, a minion that can never be fully killed and thrives off of multiple spells being cast. This will also benefit tremendously if Rogues get another quality Echo card
Kingsbane that gives the class infinite lasting potential
Sonya Shadowdancer allows duplication of valuable minions and resources if not immediately dealt with
And now Face Collector potentially contains multiple legendary cards in one (admittedly, the value of this selection is uncontrollable)
In each case, it is a concentration of value. It allows the class to dedicate more slots to removal and other functionality while giving it the lasting potential to not be a free win to other slow decks. I am not proposing that control Rogue is a hidden archetype that has untapped potential. Clearly it hasn't worked, although Kingsbane Rogue has some glimmers of this tactic. This is merely to illustrate the trend.
When I saw Cheap Shot revealed yesterday, another piece fell into place. It is a flexible, cheap removal spell that is valuable against both fast and slow decks, but remains in the Rogue flavor of single-target rather than AoE. It's good against Knife Juggler as well as The Lich King. Now, this one card doesn't make the control archetype valuable, but it helps.
However, what remains is healing. As much as Blizzard has tried to avoid it, it is simply not possible to play the long game reliably without healing (you see them caving in with Frost Lich Jaina as well for Mage). Leeching Poison gives the current Kingsbane Rogue the power to keep going, but that requires a large number of cards, many of which are rotating out, to be viable. It makes me wonder if hiding in the wings isn't a card like: "(2) Deadly Pirate: 2/1, Echo, Battlecry: Give your weapon +1 attack." In other words, yet another concentration of flexible value that frees up deck slots and can be used to defend against early aggression or held until late against control.
Anyway, I know this was a lot of wordage and likely won't be read, but I felt like putting my thoughts down somewhere. Thanks to those who made it this far.
Blizzard really likes to push weird archetypes into classes that don't fit. If they want rogues to be more control oriented, they need to give them board clears and some healing. There is just no way around it. And rogue's hero power is just very tempo oriented. You gain 2 pings but you need to sacrifice some health compared to mages. If they designed rogue to be a tempo class, why change it now?
Sonya just gives battlecries and deathrattles of the minions (1/1s), it's not like duplicating exactly by the way. It is a big difference. You basicly play sonya for additional effect, not for value.
I think the "why change it now" is "because it's stale." They don't want Hearthstone to be the same classes filling the same roles playing decks that use similar mechanics, only differing slightly from previous iterations. I admire them, honestly, for holding to class identity when it's so tempting to copy what works. It's the difference between developers and players.