I never considered myself a songwriter, but now since I've been working with Nick Lowe, I am contributing to an extent. But I'm the guitarist and he's not, so we compliment each other in a way.
I'm not particularly good at anything. I'm not an incredible guitarist or piano player or songwriter. I think what I do is, when I notice someone is really good at something, I try to get that out of them.
If you're a guitarist, you should not be intimidated by using your instrument as a synthesizer, but you shouldn't feel that you have to own one, either.