Personally I think the best solution for is this is one of three things. And I know this isn't a suggestion thread, or takes part of the suggestion subforum, but I figured I'd leave in my bit here. Personally, I don't mind the fact that you now have to farm for Dragonball Mobs, not at all. After all, in an MMO farming and grinding is part of the experience of leveling. The one thing however that I can see, is that not all classes are farming or PvE based classes in its entirety. For that reason perhaps my first solution would be the best. Rather than making Dragonball Mobs visible and killable by everyone, why not try and alter the system so that instead it's client based. Sure, you can make it so that some Dragonball Mobs are visible and killable by everyone, but why not make it so that some mobs only the player can see from their perspective, just like modded Dogis and such. This would make Dragonball hunting a bit easier, and less tedious. Because right now, with a playerbase of 5000+ people, it'll be next to impossible to find Dragonball Mobs or unused areas this late in the level cap.
My second solution is to revert to the old system, however add it so that the amount of Dragonball Mobs that spawn is a lot greater. This way people won't necessarily have to steal Dragonball Mobs from each other, which is quite rude and can get very annoying and tedious during the later hours of the Dragonball hunt, especially the one during the evening/afternoon. This way, while the spawn rate of the mobs would be easier, the drop rate can stay the same. This may make getting things like Super Saiyan, HTB2 and the Dragon Buffs quite easy, but it would be a win-win for the community in the fact that no one would honestly complain about it either.
My third and final solution is to keep the current system in play, but maybe it so that the spawn rate of a Dragonball Mob is upped from 20% to at least 50% or even higher. This'll, much like the second solution, make it far easier for everyone to at least be able to spawn in Dragonball Mobs, while also being able to farm with parties, guilds, friends, etc. Personally I'd like this option the best, as it tells players that, rather than flying around and trying to find Dragonball Mobs like they do now, to find friends and start farming for Dragonball Mobs together and try to get Dragonballs that way.
A friend/guild mate of mine did the last option, farming in one location, and we saw how many players came by trying to steal the Dragonball Mobs that we worked hard for to spawn in, stealing them for their own kills to try and get Dragonball Mobs. Now, while I understand that farming is annoying and tedious at times, especially if the Dragonball Mob spawn rate is so low, and the Dragonball drop is quite low too, it becomes RNG within RNG. So, my suggestion/solution for this is to go for the second or third option. Maybe a mixture of the two to make things less aggrevating when it comes to actively farming for Dragonballs for Super Saiyan, HTB2 and the Dragon Buffs.