It has been ZERO DAYS since some GPL'd software made me "agree" to the GPL while installing it.

The GPL is not that kind of license: You don't need to agree to it. Agreeing to it changes nothing.

This just happens because installers have a premade "license" page and the GPL license seems like a natural fit.

But there's no point: You need to notify the user the software is GPL, but that's all.

This raises an interesting question. Would a variant of the GPL that is otherwise identical, but requires that the user consent to the terms of the GPL in order to use the software, still be considered free software? In theory, this could be seen as restricting the user's freedom to run the software as they wish.
@Alex Wait, doesn't that mean that, in the scenario shown above, the installer is automatically non-compliant with any existing GPL versions? Or is there a valid argument of "technically it isn't directly preventing you from running the program, its just refusing to install it"?