Recently I've run it toplane with Illaoi/Cassi paired with flash, and jungle with Udyr paired with smite. Lower CDR than flash for Udyr, allows me an extra peeling tool but also a way to ruin any 1v1's early, meaning I can drop exhaust in a lane i'm ganking to pretty much guarantee a blown flash or kill (sometimes both because udyr you know), or catch a jungler out and just murder them which, as it has a 90 second sooner cooldown than flash, allows me to buy a control and use both my wards in their jungle to immediately invade them when it's back up regardless of their hp, which only gets worse if I catch them low earlier. Toplane, it allows me to ruin any hard engage champs, bait out certain ults, or to turn a 2v1 moment around usually.
I agree that it should be buffed/changed in a damage meta like this, but the problem is it's still a good tool in certain scenarios and I'd hate to see it compensation nerfed because it was overbuffed. It would be interesting if it was stronger on champs that don't have a lot of health or scales based on missing %hp, or any allies missing %hp nearby, or increased effectiveness against the person who used the summoner, but a lot of that is hidden power, and league is against that unless it's offensive.
I think there should honestly be two separate types of exhaust, similar to how there is heal and barrier right now, one that reduces all damage and slows, like exhaust is now, for a shorter duration, and one that just reduces adaptive force, but not as or ms, for a slightly longer duration (maybe 5-6 seconds). As it stands, you can't really exhaust a zed that ulted until at least half a second after he reappears, so you can't exhaust before ult without his ult+ electrocute being effected, and a lot of times a zed will be using q+e immediately after, so you'll either miss those two or ult+ele, but a longer duration one would be better in that scenario. Other champs, like Katarina and Akali, who are designed around being in there for longer and jumping around to be slippery, would also be better for the longer duration.
Perhaps there would also be use for a summoner that increases defenses based on bonus mr + armor, but not to allow it to feed into aftershock, but if you make it scale based on total ar + mr it would make squishies take it as denial instead, so I would lean more towards the two separate exhausts