Beginning with my mission to Switzerland, I've sometimes encountered a response to Latter-day Saint claims of additional scripture that asks, rhetorically, "We're unable to live up to what we already have in the Bible, so what good would it do us to have more?" But this seems a pretty flimsy reason for dismissing the possibility, at least, of further revelation.
After all, most of us haven't yet fully mastered even Matthew 5-7, the three chapters of Christ's Sermon on the Mount. (Perhaps, of course, you're an exception.)