Why was Death to the Daleks fully released on VHS but never on DVD?

Episode 1 was considered lost until a black and white print was found. Although it was OK for low-definition VHS release, it was not considered good enough for higher-resolution DVD. BBC Video has undertaken to restore (and recolor) a number of Pertwee-era episodes, and are in the process of releasing them to DVD. Death to the Daleks was issued to DVD with the first episode restored in 2012.