wud have to change a lot of systems. Map size is limited okay, cant make a randoimly giant map bigger than anything we have currently to spawn 10 mobs.
So we're talking maybe 4-5 mobs spawned at one time. Then you have to make it so its not possible to mob them together. This means writing new code to lose aggro and heal regardless of taunt or dmg taken. Then you have to make this mob even worth the fight. It has more hp, gives more exp. few mobs, means KSing wud be just lame for a server of 200+ players like on SEA. Can u afk kill this or need to work and cordinate and move? Then why would classes with single target be there? Wud be a bunch of players, so theyd be forced to party anyway. and aoe or single target wuddnt even matter when killing it. There's no adv. Also, what lv is this? Howdd the single target player get to the level to fight this mob? Is this their reward? lol. As the game grows this map wouldn't scale well. With KS rules, saying max 5 players allowed to camp the entire map only?
If you play a single target character, you just need to kill single mobs faster than u can mob them. and use splash lol. Was it only what, last month or whatever, before shinobi where single target rogue was the best roll. Soloing bosses, killing all mobs very fast. I updated my rogue and my dmg is still insane. I can kill single targets faster than I can mob them.
Maps with low density are disliked in this game, and giant mobs don't offer any unique or fun challenges. Seems like the only accomplishment would be to make it easier for ppl with bad gear or glass cannons :p