One thing that’s been mentioned before is content for different group sizes. We have solo stuff, 5-man stuff (dungeons), 10-man stuff (raids), and giant PUG group stuff (world bosses and public events). What about the groups of two or three? That’s where the aberrations really seemed to shine to me.
Right now, the 2-3 man content seems to consist of the “witch” group at one end of that tunnel in the Highsteppe region, the large group outside the Mine Dungeon, and the occasional two to four mob groups scattered around. The difference between these groups and aberrations is the strategies and mechanics of these groups is no different than those of the individual mobs - the only reason they require group effort is the sheer number that aggro when you attack.
Aberrations used to fill this gap pretty well. If we had a dungeon run scheduled and a couple people didn’t show up, we’d go kill aberrations for a while until enough people showed up. Or if we wanted to relax a bit but still do stuff, we’d go after aberrations rather than try to organize a dungeon. The mechanics were varied and challenging without requiring a lot of practice with the same group, making it possible to group up with strangers and successfully kill the aberrations.
As far as where to put them? Wastelands or designate one corner of the hulthines area as level 30? Or, like Logan said, put them in caves scattered throughout the map.