First it's about quality
With the advent of larger and larger television screens and high definition TV, there is a market for recording digitally, rather than the old analog VHS method. These larger screens present grand views with what can be grand sized defects. If the quality is not there, you might not notice on your kitchen set...rest assured you will on your new 40 inch plasma set.
One upping the garbage in garbage out edict, average quality TV in, markedly poor quality out. It makes sense that if you are emptying your wallet for one of these plasma beauties, you will want to view the highest quality programming possible.
With high definition TV being eased in and newer sets having the all digital DVI and HDMI connections, you will have access to a premiere picture for your viewing discretion. The DVR's allow you to then watch this wonderful technology whenever you want, at the same quality that is presented on your screen.