A lot of games sell randomized packs for real world money. Lots of F2P games, FIFA, and Halo 5 for example. It is awful. Bungie already sold randomized legendary masks for real world currency during the festival of the lost. You only had a chance to get the skull mask too.
I find it hard to believe they would let cosmetics that went on sale a short while ago "go free" now. Backlash from people who paid money for them would be huge. And more importantly no one would buy the new ones, expecting them to instead "go free" too after a few more months.
I generally agree, I was just outlining the only circumstance in which I think randomized emotes would be acceptable, from the standpoint of the player base.
In particular, anyone already uncomfortable with micro transactions in Destiny would feel the water getting a bit closer to boiling. The introduction of micro transactions to Destiny seems to have gone over very well: it's non-intrusively added to the game, purely cosmetic and Bungie clearly sold a ton of silver if the charts we saw were any indication. But a lot of people are still waiting for the other shoe to drop, for Bungie to charge $10 for the year 2 'Horn.
I don't think that will ever happen, but shifting the model this quickly, from "buy this thing you want" to "pay for a chance to get the thing you want" would do nothing to allay those fears. It would be a step in an unpleasant direction, changing the discussion from supporting the Live team, to simply being greedy by extending RNG to a system that already appeared to be working well.
(There are some parallels to the Festival of the Lost, but I think that was different enough that I wouldn't equate them.)