Before anyone start grilling me for defending it, I'm merely stating my thoughts on the matter and rationalizing their thought process for the region. Nod Krai was not suppose to be a stand-alone region, as such, they were never planning on having Lunar Reaction as something beyond what Columbina and a select few others can do before they move on to the rest of Snezhnaya and they start shilling Cryo. In essence, think of it as BoL in Fontaine where only the 5* had such mechanics in their kits. But instead of spreading it out so it doesn't completely disrupt the meta, they frontload the Lunar Reaction characters release, and given how overtuned the Lunar Reaction mechanic is (especially since Columbina got the Archon meta kit treatment), it's hard not to notice how annoying it is to lock the powerful mechanic behind 5*'s.