There is no reason for the project to change into a defi project because not all defi projects are success.
Maybe the team changed it to defi and hoping it can brings more people and investors to their project.
Better to stay focus on main purpose of the project than change it to a defi project.
It is what they think is best for their project to also go with the defis because they are thinking that defi projects are all successful. But op is right to say that investors shouldn't rely depend on the developers if they create a defi, it's not an indication that it will become successful just because others became defi.
Often times, the investors are at fault.