Yes, it is a shame. But: I will add it, along with Windows support.
Indeed, I'll go further. I'm really starting to believe that the only way not to get royally screwed as an app developer is by abandoning the "major" platforms -- which all want to turn you into a serf -- and target OSS platforms like Linux. I'm honestly tiring of dealing with the artificial roadblocks Apple (and Microsoft is no better) throw at me to further their own ends. I actually analysed SteamOS with this intent, but sadly it looks like SteamOS is geared towards the "living room" experience.
Anyway, long story short: there will be Linux support in 2018.