I wonder if even half of S4 users have those features turned on?
Beyond that though, I would suspect they'd have to write code to accomplish all of what Samsung did with it's programs, unless maybe Samsung would license the code to them on the condition that the code only be turned on for Samsung phones.
Finally, I suspect there's a significant size penalty for all of this code. The S4 probably comes with less free space than any other phone of the same memory size (less free space of all the 16GB phones, etc.). I'm not sure the app makers are going to want to take that hit for what is basically a gimmick to sell cell phones.