The difference here, though, from the LP->CD scenario, is that in the case of music, and arguably of DVD/HD movies - the benefit of buying in a newer format (e.g., ogg vs. mp3, some newer form of media than DVDs/Bluray) is not noticed by the poblic.
MP3s above 160kb/s are, for most people (I know not you eagle eared perfectionists) indistinguishable from 256/320kb/s mp3s or FLAC or OGG under normal listening circumstances using normal headphones...there isn't a lot of purpose to repurchasing as there was prior to CDs. The LP/Tape -> CD migration resulted in people getting something they could hear was better under normal conditions (car, living room, bar, headphones etc).
From VHS->(laser disc)->DVD also resulted in a visible improvement. HD again shows a visible improvement, but I doubt we'll see another hardware format take off like Blueray is trying to do - and by that I mean, people repurchasing their collections. I think that the visible improvements, for the average Joe, will (for movies filmed up to now, anyway), not be significant enough to warrant repurchasing in a 'new' format. Most people won't see the difference and/or be able to appreciate it enough to want/need to repurchase. Sure, 3d-scent-o-vision-based-holograms may necessitate the change, but those things won't really 'improve' normal 2d movies as we watch them now. When we all have 4096P wall-screens, maybe...but I think that's a little ways away.
Books? For the standard book that consists of simple text, there's not really a need to buy new formats once you have one. Unless DRM gets in the way. And as most acknowledge, the people that are inconvenienced by DRM aren't the pirates/copiers...it's the normal user who can't a)remove the DRM on their own b)doesn't know about it c)doesn't know where to get the same thing without DRM.
I maintain that the best DRM is social with the author developing a relationship with his reader ... and the reader who 'knows' the author, and feels invested in their work and success will be the ones who continue to financially support that author. The authors who remain aloof, don't communicate with their audience etc, won't find the same audience support AND will a higher piracy
urchase ratio than the friendly author (book quality being equal).