Update - I have an O-A visa (from 10/2019). After spending a few days outside of Thailand, My return to the kingdom yesterday was without problems and I got a visa for another year (Suvarnabhumi).
I was not asked to show any health insurance.
TLDR : Answer Summary
The post discusses the recent experience of a user re-entering Thailand on an O-A visa without being asked for health insurance, contrasting it with mixed reports from others regarding the enforcement of insurance requirements. The comments highlight concerns about future requirements and experiences among different Immigration Officers.