I am in a job where I have a lot of hands-on work with clients. I am project manager, programmer, and executioner in one. I know there are a lot of people who never meet their clients face-to-face or even call them. I find that this experience, while somewhat time consuming, is an absolute must in order to maintain sanity and a balanced view.
Just the other day I was getting into a project, having not met the client, and started to get irked by some of the client's email comments. There was nothing outwardly bad about what they were saying, but I started to read into things. I was getting irritated. Now, this doesn't happen very often, but sometimes, you just get rubbed the wrong way.
But then, I finally had a sit-down meeting with the client and found out that he was a great guy. Very pleasant to be with and above all, he was very excited about the project and the progress that had been made so far. Knowing this, understanding that I was getting irked for no reason, completely changed my outlook on the project. Suddenly, my attitude was totally positive and my enthusiasm was pumped up.
I can't imagine people who have to go through this experience client after client without ever having the moment of clarity that I had. Meeting your clients, while it can be frustrating and hard, is totally essential.