I used to write a lot, and read a lot. And then I got interested in my own characters and my own stories and it sort of dropped off my radar.
I got sick of reading horribly written stories, slash fics, and all sorts of nonsense like that. I'll occassionally check out fanfiction if it's a dry period for a certain show and I just need a new story with those characters, but for the most part, I do fine without it.
I still get ideas and dabble from time to time, but nothing published. I don't put most of my stuff on the net anymore. I let close friends and family read it if they are interested. Not to sound arrogant, but I think I'm pretty good at it, I just don't feel like it anymore. As much as I like writing about the Doctor, writing about Sydney Quinn and Sherlock Smith (named for Sherlock Holmes) is much more interesting and fun to me.
I will say, though, I don't think fan fiction is all that bad. Okay, so the stories might be bad, but I mean for the writers. Through writing fan fiction, I learned how to write. How to construct a story and deal with characters. And I think that for anyone who is interested in writing, fan fiction is a good jumping off point. It's a safe way to start because you don't have to come up with the universe, the characters (or at least not all of them) and everything that goes with them, you just have to come up with the plot. And I think that by playing with others' creations, you learn how to create your own, and if everything goes well, move on to original stuff.
I'm not saying that people should start fan fiction and stay there, but I think it's a good place to start. Of course, if you start writing and decide you hate it, then writing isn't for you. I know that because of my fan fiction days, I love creating stories and characters and whatnot. If it hadn't been for fan fiction, I never would've developed that part of my creativeness. And then I wouldn't be getting a minor in writing at college.