Doing its job too well. I've had just as many pre 20 games this patch alone as I've had the last 2 seasons.
Rift herald only didn't get attention before because it was harder to kill than dragon and it only gave an effect to one team member that would only charge when there weren't team members around. It was still really powerful because you could take down turrets faster over longer periods of time and dueling was x10 easier. But it was still limited to just a splitpush thing so the jungler wouldn't bother with it most of the time because the dragon could grant more pressure as a team. The difference is the new herald is overtuned and is killed too easily. You can get a turret and a half on your own or at least 2-3 turrets when grouped. It forces at least another team member to respond to the threat because the herald is just such a dominating factor that the one laner isn't enough to deal with the problem on their own.
It's too powerful and your argument ignores the entire point of the post. If the herald had the effect of destroying the enemy nexus than it would also end games quicker and force teams to control the area.
It's doing its job too well.