Aetherytes, Garleans, and You!

[Mysterysword]

Seriously, why the heck would anyone build a device that only activates when someone stands in it and twiddles their thumbs for a minute?

Note that most of those devices happen to be in rather hazardous areas. Off the top of my head, only the first and last sections of the dungeon have them. In the first section, we see those devices everywhere, apparently being used to trap the ahriman flying around in those tunnels, and none of them were inside the purple protection crystals. In the third section, we have two blue circles at once, both smack dab in the range of giant exploding crystals.

So maybe those devices weren't actually the main way to open the gates, just really stupid traps that somehow allow intruders to unlock the gates if they survive long enough.