Prop 8 and the LDS church: a query

I have about had it with the LDS church and Prop 8 in California. Why is this such an important issue to the Church? I stopped attending church about 11 years ago. These days I go along, live and let live more or less, mostly out of respect for my family. I think religion is a personal choice--it works for some people, it doesn't work for others. That's fine. I even joined the "Mormons are Christians" cause on Facebook because it bothers me when people assert that they aren't--out of unfamiliarity with the doctrine or for other reasons.

But this is just over the line. Why is the leadership so motivated to persecute a disfavored minority? Do they have any idea of the consequences of what they are doing? Don't they realize that what they are doing will ultimately fail and only damage the institution's long-term viability?

I guess not. More on this to come.