Because, it's not about adding a new feature, it's about how people use it and if people use it the way they want them to use it then it would be a good job, but if people dislike it and abuse it and what not then it would create more problems for them than solutions.
Atleast they are creating something new for the community though instead of copying it from another site. Well Im good even if they copy a good feature from another site but this is a fresh new idea.
In fact, Rollbit has been pretty creative with their latest feature but most players just wouldnt give a bat. Players rather play their regular slots then leave most of the time rather than trying all those new features