Both new delivery vectors (viral vector and mRNA) needed some time to develop, but they were not developed especially for coronaviruses or with SARS in mind. They are delivery vectors that can get produced in huge amounts as soon as the RNA or DNA sequence of the targeted virus is known. This makes these vaccines valuable in case of a biological war, they allow for an immediate reaction with millions of doses. But they were untested, and they need long term trials with small groups of volunteers. The "the end justifies the means" people at UN, CDC and FDA think that this takes too long and that it is ok to kill a million people with huge trials now because these vaccines can save the lives of hundreds of millions in the future.