I think it is pretty simple reality that teaching is not for everyone. Indeed, if it's a problem, or you find it tiring, it is ok to refuse to be a teacher and just be a student. The main teacher at any dojo should not hold it against you. After all, the main teacher at any dojo has the real responsibility, and has to carry the ball. If you think it is important that you be a teacher, but teaching bothers you, that is just your ego. If you think the students are dependent on you, again, that is your ego. Good luck.
I'm gonna have to disagree with Mark. It is your responsibility to teach. There is a (perhaps unspoken) agreement when you join a dojo, your seniors will teach you. You will learn from them. When you become senior, you pass that knowledge along to your juniors. As you progress (gain a new rank) you gain responsibilities.
Martial arts should not be a "good 'ol boys" club where the people at the top get all the perks and the people at the bottom have to do all the work; leave that to the mafia and corporate america... Everytime you rank-up, you are saying "I agree to take on the responsibility of helping my juniors, peers, and seniors. The juniors are helped by offering instruction, the peers by offering productive challenges ("dilemma rich atmosphere" - Aaron Clark-Sensei), and the instructors by doing the previous two while simultaneously improving in your own practice."
At some point in our society we created this ideological demarkation line: you are a student [u]or[u] you are a teacher. That's the same as saying, once you are a teacher, you know everything and stop learning. That just makes no sense. A teacher is a student who doesn't have their teacher conveniently handy, so they must become their own teacher for 95%+ of the time. My current teacher is 5th Dan. His two teachers are in different time zones and he sees them just a few days out of the year. He has to progress by monitoring his own practice and use his students as the catalyst for his learning.
My previous teacher was 2nd Dan. If he was going to stop learning just because he was now the "teacher" I would have great pity for him. Now that I'm 2nd Dan I realize how little knowledge that really entails. Yet, I have the responsibility, when I am the senior person on the mat, to instruct the class. It's not something I'm comfortable with, but the dojo should not be a comfortable place. It should be a place that puts you out of your comfort zone and into a place where you may be challenged to better yourself. At a certain point, becoming technically efficient at physical conflict takes a back-seat to learning how we absorb those abilities, how we pass them on to others, and why we even bother. It's at that point that teachers learn and students are taught.
To get back on the subject of teaching or not teaching, IMHO, it's poor payment to the people who taught you to say "I will take, but I will not give".
Okay, I've stood on the pedestal long enough. My legs are tired now.