Because, as I wrote, free software is about protecting the freedoms of the user, who in the case of hosted GPL software has very little rights, while the AGPL protects the user's rights to inspect, modify, and share the software they are using.

Also, it's obviously not true that they create licenses that make it impossible to make money - it is perfectly fine to make money by offering hosting of AGPL software, it's just not acceptable to lock users in to your hosting offering (as far as the FSF is concerned/if you are using AGPL software), as that limits the user's freedom.

Now, you are right, of course, that this prevents you from making money by locking in your users, for example. But first of all, that's obviously not the same as making it impossible to make money, and secondly, the intention behind it is not to prevent anyone from making money, which is also why your observation is just flat-out wrong that they make a new license "every time someone figures out how to make money with GPL software" - really, I can barely believe that you really think that, given just how many people and companies are making money with GPL software, and have been doing so for many years without anyone trying to change anything about that: Manufacturers selling home routers (GPLed Linux kernel inside), companies hosting their file servers on Samba (GPLv3) as infrastructure for their business, software development companies and consultants offering the development of customisations of GPLed software, hosting companies offering hosting of GPLed and AGPLed software, ... they are all making money with GPL software, and the FSF and RMS are happy about it - were you really not aware that all of that is happening?

Now, user lockin is something that the FSF would consider unethical, and as such it indeed is intentional that you should not be able to do that with (A)GPLed software, because they consider the freedom of the user in this case to be more important than your interest in making money from them being locked in (that's a bit like how society in general nowadays considers the right of humans not to be owned to be more important than the interest of slave owners to make money off their slaves' work--that does not mean, though, that the abolishment of slavery had anything to do with preventing anyone from making money, it was about human liberty, and that you couldn't make money using slave labor anymore was just a side effect and not the primary goal, and, after all, you even still could hire the former slaves to work for your business, you just could not own them anymore).

There might also be methods of making money with software that might be perfectly ethical, even by the FSF's standard, and which still are prevented by the GPL. Those cases tend to be unfortunate side effects of the fact that the GPL is a general-purpose license that has to be written to be applicable in as wide a range of cases as possible.

You might also want to read the FSF's definition of free software (or at least the first few paragraphs if the whole thing is too long for your taste):

http://www.gnu.org/philosophy/free-sw.html

Also, I just noticed this more verbose explanation of how and why selling free software is perfectly fine:

http://www.gnu.org/philosophy/selling.html