neural nets at the same time require multiple passes through the data (epochs).
if we can train a model in one epoch jnstead of 10000 epochs thats a breakthrough!
Furthermore, number of parameters do not (necessarily) grow with the size of the training data, can be reused if you get more data, can be quantized/pruned/etc. There's not really an easy way to do these things with SVMs as far as I understand.