I suppose this post could be called "choosing your battles" as well...but I'm not kidding about the pointlessness.
I think that today's teacher's pointless rules are developed from out very own school experiences. We remember teachers who were deathly opposed to gum chewing or using red pen to do math homework and we decide, "Hey, if those rules were good enough for them..."
I remember with fondness one particular rule from high school French class. All work that was peer edited (on a daily basis) needed to be corrected in GREEN PEN. Now this managed to create all kinds of unforeseen difficulties. 1st, in the course of a year, you find yourself needing at least 2 of these pens because one always seems to get lost, dried up, eaten by the dog, etc. However, green pens (and maybe this has changed since my childhood days) only come in packs with about a billion other multicolored pens. Unfortunately, students in my high school were not allowed to use any of the other beautifully colored pens for their other assignments in any other class. I imagine that if someone had started to manufacture boxes of green pens during that time period, a French student could have made a fortune peddling their wares. And the silly thing is, parents didn't get up in arms about the situation, they just followed the rules year after year wasting their money trying to get their students what they "needed" in order to be productive members of their classroom.
This leads us to the point...
The importance of rules:
1. Establish classroom authority.
2. Enhance the efficiency of the class.
3. Create safety and respect.
Simply put, if your classroom rules are nitpicking things that are not helping the classroom run smoothly, you will waste time trying to enforce them. Students need rules and discipline, but if there is no clear and direct purpose (except for the sake of having rules) students will not understand or respect them.