“some moral laws may be designed to minimize human suffering and maximize human flourishing long term.”
ALL moral laws are “designed” for that.
And actually they are not so much designed as learned. Learned through the school of hard knocks, ie, centuries of experience.
“Moral laws” are really “nothing more” than rules for living which when followed will likely result in more long term happiness, than when not.
They make a big part of what we call values and they are the essence of any culture. They are the do’s and don’ts that are ingrained in all of us from childhood on.
They also make up a big part of any religion.
When I was growing up and learning from my Depression Era parents I was taught certain absolutes. Things you just don’t do. We were only told why in doses and when maturity and example presented opportunity.
Mostly, you are correct, the reason not to do certain things is that things just work out better if you don’t. People have learned these things over time and try to help younger people not have to learn them again and suffer the consequences all over again.
In high screwl I had an engrish teacher as a senior named Lucretia. She scoffed at my take on tradition being things that have stood the test of time as being small minded and unsophisticated. She was also one of those who eventually screwed up her life. In time I got to laugh at her and did. It was delicious. At the time I was able to drop her class and switch to Speech instead, that served me much better than more engrish. It did a lot to prepare me for my profession.