Patience is a virtue. It's tough to hold a reader's attention for a long period of time if you aren't a highly experienced author. Flash fiction pieces help to solve this problem.
Another great thing about flash fiction is that it can be used to experiment. I had never written anything in the horror genre before I decided to write some horror flash fiction. I still don't think that I'm ready to write a horror piece beyond a thousand words or two, but I'm more confident with writing it now that I have some experience. Flash fiction has helped me branch out to many other genres that I had never written before.
Give flash fiction a chance, from both a reader's and a writer's viewpoint. You can test out a different genre, play with a cool magic system that's stuck in your head, or simply have fun writing whatever pops into your head. Reading flash fiction can be equally enjoyable, and even if you despise the piece that you are reading you won't waste a whole lot of time surging to the end.