Post-apocalyptic, eveyone has seen that one already

I want to write my first rpg supplement for my own rules set. But now the genre or setting I'd like to write the most is post-apocalyptic one. But there is one problem.

World is full of post-apocalyptic stuff. Movies, games, roleplaying games, books, comics and so on. Why should I write yet another post-apocalyptic setting? Someone might say, that if it has an unique twist, it is worth it. But meh, if there is no special twist or something new?

I mean, I am not sure do I have any new ideas. I am not sure could I bring something new into post-apocalyptic genre. Or do something better than it's already done.

Why would I like to write one then? Well, for my own accomplishment. I realized thinking this urge of mine, that if I got inspiration and motivation for post-apocalyptic stuff then I should do it. It wouldn't be good to write a setting only to please other players if you don't have passion for it. I think setting you have seen dozens of times might be better if writer wanted to really do it, than a setting what was written only to sell out.

So, should I think that I write what I want to write, even if it's nothing new. Or should I try to find something what is interesting to greater masses and try to squeeze something new... in cost of my own passion?

Even though this post-apocalyptic dream of mine would be dull, it is writing. And I suppose everything you write down will advance you in some direction. No writed thing is a waste of time, is it?