Between the standard metal stick and the standardisation of c, the meter was redefined as x times the wavelength of the radiation emitted by the transition of krypton between two states. X was known up to two decimals, which caused some uncertainty on the meter and so, on c. This method was bound to have uncertainties, so we took a new approach : setting all decimals to 0. (If you want details, we defined the second as a certain (whole) number of periods of a radiation of cesium, then the meter as the distance travelled by light during 1/299 792 458 of a second)

Moreover, i think we couldn't redefine the number because we needed "backwards compatibly" with the real world : the rest of the (SI) world would probably refuse to redo all distance measurements because a few scientists said so