By there very nature, Stickies are sticky. Stuck to the top of each page within a given forum. Say for example that stickies only stuck to page 1, last month, I had my personal forum preferences set so that the page with the newest posts appeared first. In some of the forums with pages and pages of threads, I'd never see the stuck posts since delivered to my screen would be the last page first.
So on one hand, yes, you are right, it's pretty redundant when your preferences are set to show the oldest posts first. But for those with their preferences set differently, they may never see some stickies.
Hope this explains it and thank you for bringing it up - great question.
Jim