"GPL only requires you to make code available"
Apache licenses and any other open source licenses as well - the only difference is the impact on other code.
But why the need of the AGPL? Exactly because under GPL if you never redistribute a "derived work", you never have to share the code as well. Thereby all cloud providers and ASPs can "play ball" without making available any code they add or modify, under GPL and many other open source licenses. Again, it's FOSS licenses were designed for a different world - when the "enemy" was the big corporations *selling* software, Microsoft, Oracle, IBM, etc.
How much code is under AGPL? Very little. There were also some incompatibilities with GPL in the past.
Anyway, it doesn't look FSF is going to change the GPL to close those loopholes - because I'm afraid it would put it against some of its biggest supporters.... as they make tons of money using GPL software for which they'll never share any changes, since it's only used "internally".
Yet evidently a lot of software will have to avoid GPL in the future is it risks to be easily exploited by cloud providers without getting anything in return - nor money, nor code.