Just in case you didn't know, you don't have to log into the web site to install a GamersGate purchased game. In fact, the two are pretty much separated. If you run the installer a later time, it will prompt you for your account name and password. So the there is every possibility that the verification has not been performed at the time you install a game.
The ideal solution of course, would be to urge GamersGate to modify their downloader so that it is capable of distinguishing the DRM system used by games; thus if it is sent a flag or similar indicating a DRM free game, then it will no longer re-encrypt the setup.exe after installation.
But either way, for the initial installation you *will* require an Internet connection as you'll need that to download the game.
If you feel strongly enough about this topic, you should email support [at] gamersgate [dot] com and speak to them. They'll certainly listen to what you have to say.

The games GOG are given are specifically coded and arranged by the GOG team to work as a one-shot exe download with no specific release date. The games GG are given are the installation files from the publisher with a specific release date in mind.
GOG release two games a week. GG usually have two or three releases a day. They simply would not have the time or manpower to do custom offline installers for every release.

No. That's not an issue at all. Like I said, back up the temporary files and you can install from that. You don't need the downloader as the setup/install executable should be in the temp files. Then there's only as much inconvenience as if GOG went out of business.

Really? I see no launch/setup .exe in the temp folder.

You have to do it while the setup program is running. Afterwards it reverts back to the encrypted launch.dat or whatever it's called.

Then would you be connected to the Internet to do that? Wouldn't you just install the game anyway?

I bought a game from GamersGate that was labeled as DRM Free but it wanted to activate before the game would run.
I did not so it, and then wrote to GG and they looked into it and confirmed that it indeed had Tages as a form of DRM.
They refunded me my money and all was well.
Just write GG support and they should make it right.

Only the first time. Once you have a copy of the decrypted .exe you can install offline.

Honestly, "DRM Free" is just a buzz-word. As evident from this thread, everyone has their own definition of DRM.
I mean, technically, GoG is DRM.
You need to purchase the rights to the digital copy of a game before you can download it. This is verified every time you go to download the installer. The GoG website manages those digital rights :p

The folder it creates on the desktop? Well it should be possible to find it when it starts installing the game via Task Manager. Some games delete the setup exe after installation so it's wise in those cases to back up that directory actually during the installation process (basically keeping the setup exe open). But that shouldn't be the case with games labelled as DRM free anyway.

It depends on the persons definition of DRM; you bought the game from a digital download service yet expect to be able to install it while being offline?

Install it? Yes. The OP seems to think they should be able to download the bloody thing offline. But every DRM free game I've bought from GG doesn't require internet access during the installation. The only game that does, plainly states it has DRM in the description.

I blame GOG for creating an unrealistic expectation of DRM-free services. :P
Edit: damned quotes!

They should also specify that you need a monitor. People might try to play it on a server and be dismayed by the fact that A MONITOR IS REQUIRED TO PLAY THE GAME.
They should also specify that you might need a keyboard. Someone could click through, then be unable to move. They would be dismayed by the fact that A KEYBOARD IS REQUIRED TO PLAY THE GAME.
Oh, oh! What if a quadriplegic has a friend install the game for them, then is dismayed by the fact that HANDS ARE REQUIRED TO PLAY THE GAME.
Seriously though, at the very least stop randomly putting your complaint in all caps :p. Preferably realize that this is kind of a "duh" thing, but I just really find it annoying when people keep putting the same thing in caps over and over.
Unless that thing is "Ryan Reynolds is a hot piece of man-meat". Because that is just a holy truth that should be acknowledged regardless of sexual preference.