This was implemented somewhat recently, I assume to limit the ability to "hunt" warmode players.
However, I think that this has had knock-on effects that might not have been considered:
PvE issues
- Being unable to /who someone who has a question, is selling or buying something, or when forming a group, means more time is wasted on asking them their race, class and level, and not being able to see where they are can matter. For example if you know your group has enough time to run Maraudon, but not if someone has to come all the way from Hinterlands, you save a bit of time. Same with trading things like enchants, "my mats" crafts, and so on.
- When looking for something specific, such as a warlock summon, a lockpick, a tank or a healer, or even just someone to help out with a quest, you can't simply find all the people within your level range or within a particular zone and message them to see if they're available.
PvP issues
- The big, BIG one here is... it dampens PvP. Doing a /who to see how many people of the opposing faction are in your zone was one way to know where the action might be. Should a 20-something bloodthirsty alliance player go to stonetalon? Or is hillsbrad hopping right now? No way to tell at this moment. Of course, it was still a bit of a gamble before, but now you can't tell if there's nobody there because there's 8 warmode people, or if there's nobody there because it happens to be empty at this hour.
- Hunting should in fact be fine. Griefing is already against the rules, but if someone is known to be a warmoder you should be able to seek them out. The bonus to XP means they will likely outlevel those hunting them rapidly anyway, making being targetted by some obsessed person less likely. And again if its a high level repeatedly messing with someone, that's already against the rules.
- There already was no way to tell if someone was warmode or not in /who, so you couldn't simply hunt low level warmodes with it without knowing they were such ahead of time.
On Y'shaarj this may be less of an issue as there is no xfaction there, and everyone is technically warmode at all times. I don't know if maybe this was implemented because it's not viable to maintain two separate systems on the two servers or what, but I really hope the PvE server can have this change reverted. It's been quite annoying.