Lax licenses, and even the regular GPL, do not legally entitle users of a web application to the corresponding source code. The AGPL does with its copyleft-over-network "Affero" clause. If you don't think copyleft is important, or think that it's OK to permit proprietary derivative works, then the AGPL will seem like a poor license choice. I am extremely pro-copyleft, especially for applications (vs. libraries), and think the AGPL is great and fits a very important legal use-case.
What if the license were just an entitlement to your personal data? That you could take it back and share it only according to your terms rather than those of the server operators?
I think the AGPL works very well for applications that employ it. I simply think that perhaps this one shouldn't. Instead of threatening to legally bludgeon non-free versions, it should just work better or have more value than a non-free version.
I agree. While I'm not very pro copy-left in general, I think for a social network it makes more sense. If there are concerns about privacy, and the solution is open source, then why leave the door open to a proprietary version that would completely defeat the purpose of this software? It's especially ridiculous to refer to enforcing the AGPL as "legally bludgeoning" someone, since the proprietary code derived from this would presumably like to "legally bludgeon" anyone who distributed or modified their source code.
The AGPL makes code less usable than MIT, BSD, LGPL and even GPL:
Anything you can do with a piece of AGPL code you can also do with the same piece of MIT code. The opposite is not true.
The reason GPL works so well on Linux is because it doesn't affect licensing of the software that runs on top of Linux or connnects to it. AGPL works around.
The whole point of the AGPL is to ensure that derivative works give users the exact same rights that they were intended to have. It doesn't make the code less usable unless you'd like to make a proprietary derived work.
Why do you believe this, though? Would a BSD/MIT/X11 (even LGPL) license not be more appropriate?