Actually Karush Jaggi has an interesting case. Obviously, if Romania was part of Schengen, he would not keep to the rule (according to which he has to get the visa for the Schengen country his trip is mainly about). But as he is not abusing his visa for Schengen country A to go to Schengen country B, I wonder if this might have any consequences for future applications for a German visa. If he applies for another German visa in the future they can obviously see that he had a visa but never used it for entering a Schengen country, but how will his stay in Romania be considered?