Why are the 12 tribes of Israel important?

The LDS Church has a list of 13 general beliefs, which was composed by Joseph Smith in the 1830's. It does not cover everything the church believes, but is a good guide. In the 10th article of faith, it states, "We believe in the literal gathering of Israel and in the restoration of the Ten Tribes".

First of all, why do we care about the 10 tribes? None of them appeared to have any redeeming value. Israel (Jacob) had 10 juvenile delinquent sons, who tried to kill their own brother Joseph. One of these sons slept with someone he thought was a prostitute, who turned out to be his sister. Other sons slaughtered an entire group of people who had just been circumcised.

As time moved on, we learn the 12 tribes of Israel split into a northern and southern kingdom. The northern kingdom pretty much was wicked the whole time, while the southern kingdoms of Judah and Benjamin were wicked most of the time, but had more periods of obeying God.

I just don't understand why these tribes are supposed to be held in esteem, because it really doesn't appear to me that they were ever worthy of the blessings of the Lord. Everything they do in the Bible appears to show that they were generally wicked. I know that God promised Abraham, Isaac, and Jacob that they would have posterity without number, but if the children were so wicked, do they merit more consideration than any other group of people?

So the 3 questions I would like answers to are these:

(1) Why does anyone care about the lost 10 tribes?
(2) Why is this restoration of the lost 10 tribes even mentioned in the 10th article of faith?
(3) If God is no respecter of persons, do the lost 10 (or 12) tribes merit more consideration than any other group of people?

I'd love to hear what anybody has to say. These are sincere questions, are are not intended to rile anybody up, though I know they may sound heretical, hence the name of this blog.