My answer to this question is always, "why not?" Few places send the senses into overdrive like Hallstatt does. Steeped in (pre)history, built on the side of quintessential Alps topography (gorgeous limestone mountains), and famous for its salt mines (high up the mountainside), Hallstat welcomes the traveler with open, yet quiet arms.
Every person I have talked to that has visited Hallstatt has been enchanted with the place! It is a mecca for hiking and mountain biking/cycling (bikes and hiking/climbing gear can be rented in town). Late in the evening--after the tour buses leave--it becomes magical!
Although Hallstatt is becoming increasingly well-known by European travelers, it still maintains its charm even in the peak season. Most of its inhabitants can trace their families back several (often times more) generations to the exact town (if not house)! It's a little out of the way for many people, but those that have been there make the journey again and again if it is even remotely possible.
My wife thought driving from Garmische, Germany to Hallstatt was a long drive (it is), but once she saw the town, she was amazed, to say the least. And so it goes with each person who I talk to that has been there!