You can compare robots to computers in this regard. PC's are generally used for a wide variety of applications, while embedded systems typically are more dedicated devices. The short answer is in what form are they the most useful? Industrial robots are certainly more dedicated, but flexibility can also be a virtue in that environment as industrial needs change. If there is a niche that it is possible to fill, then it will tend to be filled.
No, it is fairly well established that humanoid robots aren't te best solution for something that has a specific singular task. there are only 3 real reasons to make a humanoid robot that I can think of.
1. to operate tools and equipment designed for humans with as much flexibility as possible.
2. To interact WITH humans as a companion (that is pretty thin logic).
3. just to help us research and solve problems to further our technology. (balance, gait, etc)