:0 so whats the point? why the add it, if its not available in survivor mode its the most stupid thing ever ....
also its strange if the slime is there, and already add the coal and redston block so why to wait ??
i am shocked....
To answer your question about why adding something if it's not available in survival, while I am not 4J and won't assume anything until it is mentioned by them, my guess would be that they are working up to making that change.
First they make the small minor changes and adjustments required, ie. changing the poppy/rose textures, also the change to the sponge texture in the last update. They add the necessary bits and bobs to complement the bigger change ie. adding in the new woods (albeit to creative) etc. then they make the bigger change that they are working towards, which is the new biomes.
So in the end we will likely get the new woods which should be associated with the new and biomes, again my guess
As for the slimes, yeah I don't have a clue why they haven't been added yet, but they'll likely come at some point?