Even if you did write plugins for apps and license/sell them, that would stop you from using a useful app just because you couldn't do it for that app?
I'm having a hard time following how AGPL affects you as a user of the app, not someone who's selling addons for it and not as someone who provides the app over a network.
It seems you could modify the source and run your own version without releasing your modifications and without violating the (A)GPL.
2. Yes, because I don't want to spend time learning a system that I can't extend if extending systems is my livelihood.
3. I don't want to support a community that shuns people who disagree about licensing.
4. This feels against the spirit of open source to me, to avoid having people use code, and provide feedback.
I don't believe that anyone understands the GPL including its creators. Too many things in it are vague.
AGPL: Anyone using/visiting the service need to have access to the source code.
They are very simple. The only reason people can be confused by those two is FUD, and lawyers who find such statements too simplistic.
The AGPL want that anyone who uses a service also have access to the source code. If one runs a modified AGPL service that only one person have access to, then the set of people who need to have access to the source code is that one.
That "ugliness" you mention has worked really well for my career and I know more people that think the same than people that think the opposite.