I went in to see someone basically for my TS feelings, and I actually was afraid that I would get sidetracked on 'other issues'. In the end, I did end up also confronting a lot of my personal concerns and problems, but many of them weren't unrelated to being trans. My therapist was no expert at all in gender identity, but he helped me a lot simply by being someone I could vent all my fears and frustrations on, and who would help me keep my problems in context. I had a bad tendency of withdrawing and trying to bury my problems at times, gender issues included. So, along with giving me the opportunity to figure my identity and desires out, he's helped me to sort out my life... if only by prodding me to keep asking myself tough questions.
If you really feel like you know what you need and where you're going, perhaps therapy isn't all that important. However, being trans, or even normal life, often involves personal and social issues that can cause a lot of stress. A good therapist can help you get over your difficulties, whether they're explicitly trans-related or not.
