Bingowings said:

It is nuts the number of totally unremarkable films that get multiple releases when films like this one doesn't even get a basic release (prominent director, cult following, well known stars).

More often than not that's due to legal issues, usually producers and the various investors/production companies that teamed up to produce the film. They have to get all that sorted out before a DVD release can happen, and if those people aren't available for whatever reason - not in the biz anymore, dead, working elsewhere and can't be associated with the former partners, etc. - then films get stuck in video release limbo.