Who are you?

"Every member a missionary!" That's what you're told from day one, but that will never be more clear than when you leave the church. Even if you still believe but have fallen into inactivity, or worse, the dreaded doubt you will become every members' favorite project.
People who live three houses away will mourn the loss of your presence in their lives while failing to realize that they can still contact you at any time. They don't even need to bribe you with fresh, hot cookies (though that doesn't hurt)
I've heard from some fellow exmos that they have been approached by complete strangers and fed the "I miss seeing you!" line, which would promptly turn awkward when it was pointed out that they did not in fact know each other.

-ECoG

So why did you REALLY leave the church?

Being a Mormon means feeling like you're part of something special. From the day you're old enough to learn, you are taught that you have the secrets to the one true path to happiness. Because of this, members have a hard time understanding why others would want to leave.
We can list all the reasons we want, from Joseph Smith's marriage to 14 year old girls, or sexual interrogations of minors but it will almost always fall on deaf ears.
It is so much easier to paint us all as bitter, angry apostates who got offended by one of the "non perfect" members of the church. Or degenerates who just want to drink and have butt loads of premarital sex (hehe)

Its a slow, uphill battle, but I think with the church releasing the new "tough issues" essays, people may find it easier to understand where we're coming from.... Hopefully