Joseph Smith said when asked how he keeps Mormons in line, "I teach them correct principles, and let them Govern themselves." As such the idea of policing the members is a moot point.
Is it unethical then, for church leaders to agree to refrain from actions on behalf of their members?
Short answer: Church leaders are in no position to make promises for their members. But stating new church policies is not unethical.
Mmmm... that's kind of a misleading question I think. If they did that, then it would be an abuse of power. They cannot definitively speak for everyone in the church. Church leaders have the responsibility for speaking for a religion as a whole. They are the spokesperson for an entire belief system. But I think we often treat them like CEO's of a corperation who can install new policies and guidelines and then fire people if they don't follow it. Religion doesn't work that way. It is a way of life and a mindset you live in. A belief in a higher power and how that effects your life. At its core is the idea that despite all the rules that exist, nobody is perfect and we are all striving to be better. As such, the wording of what church leaders say is always around the lines of "We've asked our members not to... " when it doesn't pertain to doctrine, etc. Even then there are some definitive commandments, but if a member doesn't follow it, that doesn't make the leader bad either way. But if an annoucement is made about a new policy and you are one of the many people who are chronically 20 mins. late for church, you'll never get the annoucement. It isn't doctrine from the scriptures, it isn't part of the lesson plans or sermons, etc. It is a social policy.
No. I think for any religion, whether it be LDS, Catholicism, Judiasm, Muslim, etc. the ability to choose right and wrong for yourselves is essential. It is not the responsibility of Church leaders to micro-manage people's lives; it is their responsibility to lead a global church in things that are the same no matter where you are and leave the smaller details to the individuals. If the leaders pronounce one thing, and the members do another, why do we blame the entire LDS church? I've known since I was little about the Holocaust names controversy and to only research your own family for the baptisms, for a long time, that seemed to be enough... but I also know people (especially converts who didn't grow up in the church) who know nothing about it. We don't quality check the names brought into the temple usually, that would be a fulltime job all by itself. We leave it to the members to sort it out. Its a bit messy at times, and the church has been trying different ways to prevent redundancies and correct procedures for many many years via software and barcodes, and this and that. But it is a hard problem to solve especially when everyone is lay clergy. So anyway, yeah.