hm, yeah there's a few reasons to do this. one that instantly pops into my mind is stalling for the cloud to come out on yoshi's story. shine a few times so you don't just drop, and bam, eventually the cloud MAY come out and you can aim for it. otherswise, it could also throw off an edgegaurder's timing. that's just a few things that come to mind but of course there's other. mainly yeah it stops your momentum and gives you more time to think about how to recover or to stall etc.
edit/ leoneri beat me for first post. THANKS. lol