The main points have already been covered, if not a little lost in the murky depths of the thread but the overall goal is clear enough. The question becomes if the outcome will be the one desired. Bluntly put, by adding any form of mandatory credit sink you are creating a demand upon the player to dedicate a certain amount of time in order to continue playing. The closer the input and output of credits becomes, the greater the requirement upon the player.
This can be disguised, as Lyth rightly put it, by making credit earning an enjoyable task with more varied ways of making credits making the system less noticable. At the moment we have roughly four ways of generating credits: Mining, Trading, Smuggling and Missions. Unfortunately this list is also some of the more boring roles within Disco with the latter two avoiding interactions completely. Unless we can make these methods more fun, or add other forms of income any overly noticable credit sink will likely backfire.