The GPL increases your freedoms by forcing people to give back, for free, the work they've done on top of GPL'd work they in turn received for free. With software as a service, this breaks down completely, because the derived work is never actually distributed.
The GPLv3 explicitly tries to deal with software as a service, but it's definitely more problematic since it's not as solidly grounded in copyright law as v2 is, it's harder to detect breaches of it, harder to prove breaches, and harder for the people in the justice system to understand it.
> The GPL increases your freedoms by forcing people to give back, for free, the work they've done on top of GPL'd work they in turn received for free
No, the GPL forces people to distribute the source code of their own modifications, but that's only on redistribution. That's why with software as a service this doesn't work.
This has to be emphasized, because that's its central strenght.
The majority of all software is made and run in-house, without ever being distributed. And open-source would not be what it is today without contributors that have SaaS as a business model.
> The GPLv3 explicitly tries to deal with software as a service
No it doesn't. The GPLv3 is still only a copyright license which only covers redistribution (as GPLv2). It is more problematic because it tries to define what distribution means (to prevent tivoization), and copyright laws have their own definitions, but it still is within normal bounds ... so it remains to be seen if it works, but FSF has got some pretty smart lawyers over there, and they did their homework.
The license that tries to deal with SaaS is AGPL.
But that's not a copyright license anymore, and while it is considered to be "open-source", some people think that it shouldn't be, since it places restrictions on the actual usage of the software (like an EULA).
And you'll have a hard time convincing companies that have contributed to open-source to switch to AGPL. Hell will freeze over or a new gap in AGPL will be discovered before that happens. One way AGPL can be "monetized" is with dual-licensing. But that's just dishonest and definitely not free.
The GPLv3 explicitly tries to deal with software as a service, but it's definitely more problematic since it's not as solidly grounded in copyright law as v2 is, it's harder to detect breaches of it, harder to prove breaches, and harder for the people in the justice system to understand it.