While there is no doubt that MiniDV is being eclipsed by newer formats like DVD, hard disk drive (HDD), and flash memory cards, it does offer a number of advantages. MiniDV is cheap and widely accessible. It's relatively durable, though many users have experienced the frustration of a faulty tape mechanism that spills out the lengths of tape. Cassettes make for easy archiving and the capture process for editing DV is more widely available than any other media.
Most crucial, perhaps, is that DV compression generally offers better quality video than the other formats. Standard definition DVD, HDD, and flash memory camcorders all employ MPEG-2 compression, which has a much lower data rate than DV - almost 1/3 the speed (8.5Mbps versus 25Mbps). Data speed is only one component of video quality, but it is important.