They are not needed and as Nick pointed out, were not fitted in production in later years, just be sure to fit the seals to the correct depth and square if not using them.
Personally, I like them. I'd say 8 out of 10 hubs that I've pulled down that has not had them fitted has the sealed pressed in up against the Bearing Cup. In that position they do next to nothing and in any case, the lips end up damaged by the bearing. For a short time in the Leyland days, they did fit a seal spacer on the inner and outer, they where different thicknesses though - 3.5 mm on the outer and 5.5 mm on the inner. I cut and fit them as it makes the job just that bit more fool proof and easier to do when not in the workshop.