My situation is as follows: I spent my undergraduate time at one university and recently entered grad school at another university (both of them in Germany, my field is theoretical computer science).
For my Bachelor's thesis, I worked (for about two months or so) on a topic that had not been considered at the time.
My former supervisor, although he proposed the topic, is not (at least not for the last 30 years) actively doing research in that specific area, which resulted in me ending up quite on my own. However, I could get some new results. They were, of course, not groundbreaking, but sufficient for the undergraduate level and the amount of time spent working on the thesis.
So we submitted the results to a (medium-to-low-ranked) conference in the subfield. The reviews were quite mixed. Two were rather superficial: One positively and recommending acceptance, one negatively and recommending rejection (actually, the latter one was quite rude).
The third one, however, although recommending for rejection, was quite encouraging. The reviewer liked the idea of the paper, while the results we obtained did not suffice for publication at conference level but (his words) were rather suited for venues for work in progress, e.g. workshops in the area.
I actually agree with the third reviewer, for it would have been quite a surprise for me if a second-year undergraduate would have been able to produce publishable work on his own just like that, so I am not that disappointed.
My problem is that I do not plan on pursuing that specific subarea of research in the future and neither does my former supervisor. However, given that I ultimately aim for an academic career, I think it might be worth some efforts to get something published. Additionally, at my new university, nobody really cares about the area of the thesis, so chances to get some expert here to work with in order to improve the results are rather bad. This means that if I want something to happen, I would have to invest a vast amount of time and thoughts into a topic I don't want to pursue in the future, instead of entering new areas of research as quickly as possible.
So: Should I improve the results and finally get them published or should I invest the time for acquiring knowledge in a different area (and start publishing later) and abandon the work that has been done (giving away a possible publication) (w.r.t. the impact of the outcome on my academic career)?