Late stage vaccine trials are conducted by vaccinating a bunch of people and then seeing how many get infected versus a control group. So it's not just a matter of "not needed"; the trials simply couldn't be performed without an active outbreak of the disease. There was a lot of promising early-stage development.
From my understanding, they were started, but then both SARS and MERS burned out so fast that they couldn’t find enough candidates to test the vaccines by the time they got to trials.