Hex4 is fine because they run horrible units with unfitting synergies to get there.
Resulting in them being massively out-stated by champions and their synergies alone.
Hex2 is fine because it has more than enough counterplay.
Moving your units around a little. throwing irrelevant componts on other champs to bait the bomb. Use 3 Champs with 2 Items instead of 2 with 3.
Hex2 is just as much of an issue as Blitz is, or a stacked Morgana/Kennen.
Overall I dont like Hextech. It's an annoyance. But overalll weak. I'm not going for it.
Sure if I get my hands on Jayce and Vi while building Wild/Shape/Brawlers I take them. But rarely I felt like Hex deciding the fight.
The only thing worth mentioning is that Hex tends to shut down FUN-Builds ALOT harder than actual META.
You know - instant Ult-STuff, Spatula nonsense, RFC melees, immortal units.
All of this can't be actually build for if you want to win but it's hella fun if the game decides to throw it at you.
It's just sad watching your Demon/Seraph/Yuumi Kata that wipes a whole team in 2 seconds gets Hexteched and does what Kata usually always does... dieing without achieving anything remotely usefull! x'D