Well, this discussion always has a religious flavor.
My own faith as changed over time.
I used to be a Glockite, though not devout. Then, with children, I broke the situation down into first principles and thought about it from a safety/risk perspective.
Most of my civilian situations are not high-risk, but I handle the weapon a lot and need to store it when going to certain places. For me, the likelihood of ND was probably higher over the years than the likelihood of needing to shoot "tactically" or "in earnest". Yes, I know stakes are high and you can't predict the future and all, but I stood back and this is where the #s fell.
So, I ultimately decided I preferred a manual safety, and committed to training with it.
I carried the USPc variant 1 (DA/SA "krunchenticker" as Jeff Cooper referred to them) for a while.
Eventually, the convenience of pocket carry made me take a more ecumenical view and I carried a J-frame DA. But I am more scrupulous of never taking that when it might leave my person even for a second without going straight into a real safe or hard lockbox handy. And I would never shorten or lighten the pull.
Eventually I found the HK P7 and that is about the perfect solution for me. The squeeze-cock action is so intuitive that you will never forget to work the "safety" but it's damn hard to "disengage" accidentally. It's fast, slick, ambidextrous, etc. So it kind of solved the problem for me.
But, in general, for all comers I prefer an external safety. I look for guns in DA/SA or simplified safety/DAO configurations. I agree you need to practice the manual of arms thoroughly, or you risk forgetting the thumb safety.
I am not arguing that trigger discipline is not important. But safety is a sum of parts (the swiss cheese idea). Same reason we have checklists and cross-checks, standardization and all kinds of nice things that keep us all safe when flying or under anesthesia. People fail and smart systems account for this.
The people who think a 1911 thumb safety is too much to remember in the heat of action... Do they decline to use ARs as well? I always found that strange, that the orthodox Glockites will still own and use ARs. AR manual-of-arms, esp. immediate action drills, are not exactly simple.