Why isnt Starbound out on PS4 yet???

Generally speaking cross platform design is not as simple as a press of a button as most Game Engines would like you to think.
PC and Consoles require 2 completely different UI interfaces. Otherwise you get the "Bad Port" label - such as Fable Anniversary Edition. - which uses the Console User Interface for PC's.

Also this is a custom engine - which would require more work to be put into getting to work on consoles. After all consoles use different architecture vrs PC's. Though PS4 and 360 are much more similar then their previous counterparts.
Finally you need a team who knows how to program for consoles. Minecraft and Terreria both hired 3rd party teams to do console development - but only after the primary development was concluded.

Major Studios like Rockstar on the otherhand have multiple development teams specific to the console which share assets, even then there is a slight delay. Without that delay you have alot of redundancy work which will continuously occur when changes are made.
If you don''t do it without the delay you run the risk of platform specific problems - which is bad for your image. [ Bethesda - skyrim - ps3 ]

So ya - basically best practice is to finish it on one - then port it to the other. Less chances of mistakes and goes much smoother in the end of the day.