Just because the Scroll might have the capability of showing past, present and future doesn't mean that the elves can easily use it that way. Or that they would choose to use it that way even if they could. I also think we might be thinking of time too linearly. Consider what Timmain told Rayek about time. If, as this suggests, that all time is one time and it's all happening simultaneously, "past, present and future" are meaningless, and that there could be many possible "futures" that could be shown by the Scroll that may or may not come to pass. As for Orolin's role, I would guess the ability to use the Scroll in this way would require immense power and training, and not everyone could or would even want to.