Is Pamukkale worth the detour?
Pamukkale is not a bad stop; it is often a badly weighted one. Go if it fits the route cleanly, but do not bend a short Turkey trip around a place many travellers experience quickly.
Answer
Pamukkale has a clear visual hook, and for some travellers that is enough. The problem is the itinerary weight it can demand. If you are already moving through the Aegean and can visit without breaking the route, it can be a memorable stop, especially when paired with the ancient site nearby. But if you are forcing it between Istanbul, Cappadocia and the coast, the cost may be too high for the time you spend there. This is the classic Turkey detour question: not whether the place is fake, but whether your trip has room for what it asks.