PM'd since I included some personal info & context, but stripping that out here, "why I no longer feel the need to bother with trusts" (I still see value, if your scenario favors using a trust, that's cool. You don't need to defend your choice)
1. NFA transfer rules changed and they now require every trustee and successor trustee to be included on applications. That is a non-starter for me. My family members are simply NOT going to do this. And I'm fine with that. Also, they no longer require CLEO signoff, which was a big reason I setup my old NFA trust to begin with.
2. NFA transfer times have greatly sped up over recent years. To be fair, even trust times are pretty fast now.
3. Some of my old NFA items are now worthless. Easier to dispose of ancient heavy paperweight suppressors and clapped out SBR lowers as an individual without having to update trust property schedule paperwork. (This is minor.)
4. Managing the trust isn't "set it & forget it". I've had to change some successor trustees because "life happened". It wasn't fun.
5. Nobody in my family uses NFA without me there. So I personally never needed to have more people authorized to possess my NFA.
6. I used to think I'd never sell anything. Then (again) life happened, things change, and I've bought/sold items. For a trust, you have to update property schedules every time you do that.
7. My family gets a free Form 5 transfer when I die. I've left instructions for how to do that.
8. AZ is a community property state anyway. This introduces complications in the validity of simple trusts where, when I die, community property will immediately be owned by my wife regardless of what a trust says (unless it's structured to cover community property use cases, and likely signed off by my wife). I can't decide that my son is a trustee and inherits the NFA item, when it is actually community property and my wife owns it.
There are probably more reasons, but tl;dr, I find Individual forms to be easier for NFA.