It's common for certain therapy orientations. My therapist has a huge collection of toys which he uses for symbolic work, both to access unconscious material and to make the work less threatening than a direct dialogue about very deep issues. I have a collection of toys too. My colleague who has trained in psychodrama has even more toys - she has larger stuffed toys all over her office. For me the type of symbolic work my therapist does is quite useful, though lately I've been needing to work more directly than symbolically. But I think it can be a sensitive thing, since certain adults may take it as not being taken seriously or being treated like children instead of adults. I think every person can have a different experience, but if you benefit from this type of work, why not?