“I don’t like doing this, but I need to for tenure. I can’t fight the good fight for change if I don’t have tenure. Once I have tenure, things will be different.”
Tenure won’t give automatically you courage. If you’re waiting for when the time is perfect and you’re free to fight without risk, you might wait so long that you miss the fight all together.
If there is something about your department, your university, your branch of academia, that you want to see changed, start working on it now. You might not get any braver after tenure. Look around at the people who have tenure. How many of them use it to fight to make things better?
Additional, 2 September 2013: When I saw you should do something, I am not advising that you should go to war with nukes on every issue. I’m saying you should do something. It’s better than doing nothing.