A lot of ski production companies can't afford to produce their movies on Blu-Ray (which is probably why you only see MSP doing it). Freeski movies are already a small enough market as it is, so realistically, how many people do you think are gonna buy Blu-Ray ski movies? The cost will be passed on to the customer, so it'll be like what, $40/movie at least (?) which narrows the market even more.
Why dont they release an HD version available for download, this will eliminate costs associated with manufacturing and shipping of the actual Bluray disks, and will still allow people to purchase and view HD copies. They could do this through a content provider like ITunes or Bittorent
HD is just referring to the size of the video 1280X720 (720p) or 1920*1080 (1080p) however the bit-rate and codec really define the quality of the video. IMHO you can generally get very close quality to bluray with the H.264 codec at around 4Gb for a vid in 720p resolution or 8-10Gb for a vid in 1080p resolution. These files sizes are big yes, but if you have the support of content provider or distribute with torrents you'd be fine with most people having broadband connections these days. Still better than no HD at all.