Let's set aside your condescending tone and just address the content of this. You say there "no real reason" why someone might oppose the spread of the Mormon gospel or why someone might oppose their church being "bumped off" as being representative of Christ's latter-day church?
You assume most is from "anti-Mormon literature." Please explain the following Mormon Scripture to readers here (especially the bold-faced portion). This is from the Pearl of Great Price, Joseph Smith 2:18-19:
18 My object in going to inquire of the Lord was to know which of all the sects was right, that I might know which to join. No sooner, therefore, did I get possession of myself, so as to be able to speak, than I asked the Personages who stood above me in the light, which of all the sects was right (for at this time it had never entered into my heart that all were wrong)--and which I should join. 19 I was answered that I must join none of them, for they were all wrong; and the Personage who addressed me said that all their creeds were an abomination in his sight; that those professors were all corrupt; that: "they draw near to me with their lips, but their hearts are far from me, they teach for doctrines the commandments of men, having a form of godliness, but they deny the power thereof." 20 He again forbade me to join with any of them
How does all of this related to Milt Romney? If you go to http://speeches.byu.edu/reader/reader.php?id=6180, you'll see a message by one of Milt's uncles, Marion G. Romney, who was a high-ranking LDS official. Of course, Marion G. Romney cites Joseph 2:17 in this talk. I would assume Milt Romney also embraces Joseph 2:17-19.
I am not argueing LDS doctorine, right or wrong. It is not mine, nor yours, to judge.
However many (if not all) of the same values that Christians have in the world Mormons also have. Just the method of how they worship Christ is different. Your biggest problem is that they are Mormon.
Not withstanding that however it doesn't change the fact that Mormons "devoutly, thoughtfully, seriously, and prayerfully regards themselves to be Christian" (source www.religioustolerance.org) so therefor must be Christian. Christ himself even said as much.
Again the only difference is that their details, and your details may not be the same. Who is right? Who is wrong? Does it matter?
They could be any other "Christian" religion and have the same values and that would be okay, but since they carry the label Mormon you have a problem with that.