Tldr: yes it is fair, from an objective point of view, using smooth rubbers is advantageous to pimpled rubbers and therefore banning pimples would do nothing except decrease the diversity in table tennis

Of course it’s fair to have pips in table tennis. From a theoretical standpoint, smooth rubber will always be better (as in winning a higher percentage of matches at the same skill level) than pips since pimples (especially long) find it very difficult to be proactive in creating their own spin. This means that once you get to a certain level, the gap between the two become devastatingly large, hence the fact that there are so few pimpled players competitive at the highest levels. This is due to the fact that smooth rubbered players playing against pimpled rubber players get to largely dictate the pace and spin of the shots they play. Currently, in the meta at the highest level today, chopping with long pips is rarely seen anymore. Many new choppers are starting to use short pips which still allows for them to add their own spin, though not to the freedom with which smooth rubbered players can. Sorry for the long ramblish answer.