What shouldn't be done in my opinion is to focus too much on this one unique feature / mechanic.
Exactly, but this is what almost all indie games do that implement such a unique feature and it simply gets boring quite quickly.
Your argument about mobile games is valid but I don't care at all about those, sorry.
The problem with fleshed out game ideas is that I don't want to share them, I have 4+ projects to choose from for my next game and I'm not sure which of them I will realize. This is why I don't make them public here but instead post those which I will not work on myself.
