They can be but are not so necessarily and it's mostly just friendly. Imagine that parents hug their children, siblings hug each other, relatives hug each others, friends hug each other, etc, and many other cases where no sexual intent is meant. Kiss on the lips would be different for instance and though sometimes some people who are very friendly with each other do it, it leans too much towards the romance part.

In therapy I think people should do whatever makes them feel comfortable and cared for (within reason). If somebody is more touchy, a hug would do the trick. If somebody is not, or due to abuse finds hug triggering, then it should be avoided. Most therapists are mindful of this and so I think it's fine to bring it up with a T and saying you want hug (or don't want it).