The reason that vaccination has not been used up until now is that prescence of the incubating virus is detected by discovering antibodies to it in infected beasts. It would not be possible to differentiate between those animals that had already been infected before vaccination and those which were antibody immune.
Since it takes time for the vaccination to work there is the potential for the animal to be infective before the vaccine has taken full effect.
The protection offered by vaccine is apparently only short term.
From what I gather this disease is rarely fatal, the vast majority of animals get over it, but they lose weight and it costs money in time and feed to put it back.
This is an economic disease more than anything else.
One reason it has spread so fast is that the livestock industry has changed beyond recognition since the last outbreak in 1967.
Animals are moved from one location to another,in growing stages, from just weened, to young adulthood, then to be sired, then for birthing, then for settling and weening their own young, then again for specialist weight gain, and then maybe again for slaughter where the distance travelled may well involve overnight stops in holding fields.
Each stage involves movement, and then there are the normal trading transactions such as selling excess stock, or selling just when the price is best.
An animal can be moved many times in a short period, the only good thing is that that these movements are well documented, this was implemented as a result of the last outbreak, and it in those days circumstances when movements were fewer it would have been easier to control.
There have been otubreaks since 1967 but the signs were noticed very early on and the spread was controlled, in this case it appears that on the main site of infection the affected animals were not disclosed by the owner but rather by others to whom the animals had been sold and later showed signs of infection.
When inspectors arrived on the main site it seems that the signs by then were very obvious yet no report had been filed, it was only a delay of around a week but that was enough.
I have seen some reports that say that foot & mouth is the equivalent of say measles, or mumps in terms of animal health, very infectious but not usually that harmful to the animal.