Academic research often results in the creation of sensitive data. At the very least you may wish to control who has access to your research data, prior to peer review or publication, for example, and be able to determine, and keep track of, what others are authorised to do with your data.
Research data may be of a type where you are legally or contractually obliged to keep it safe and confidential. For example, raw data may contain information about persons, with concomitant responsibilities under the Data Protection Act. Certain types of data may be commercially sensitive or be protected by intellectual property agreements.
Even if the main output of your research may be your thesis, you also have to make sure you keep (and can find) other information you gather during your research, such as your notes, bibliographic references, correspondence with supervisors and so on.
Depending on the nature of the responsibilities associated with your data, you should consider range of solutions in order to mitigate the risks of inadvertently losing, exposing or compromising your research data.