Is it ethical to request additional money for non-research related work in a research lab as a grad student? I work in a computational research lab as a graduate research assistant. We're all funded under various grants to do research in our field and we are also working on a thesis, which may or may not be directly related to the funding source (it is if we are lucky!)

Our lab is also licensing the software we write to outside companies for their own in-house use. As a result, there are many "niceties" that should be added to the code to make it more user-friendly, but these have no bearing on our research, either the sponsor-funded or thesis-related. 

Is it okay that we are expected to implement these things in addition to our funded/thesis related work? Is it acceptable to ask for additional money (assuming work done on this is in addition to funded/thesis work)? 

Our advisor is considering hiring an outside company to come in and put in these features, but we would be expected to help them through the process of learning and understanding our code so it would be nice to cut out the middle man since we certainly won't get any extra money from advising the consultants.
From one perspective, adding these niceties to the software increases the likelihood that the software will be used and thereby increases the impact of your research. So although these niceties are not research per se, they help achieve the goals of doing research (at least from a funding agency's perspective), namely making an impact. Such tasks are often a necessary part of the research process (and someone has to do them).

Whether or not it is ethical to ask for additional money to hire people to do this very much depends on the rules of the funding agency and how well your advisor is at selling and justifying the idea to the agency.