But I also know that the AGPL license is usually adopted because they want to sell a commercial license, even if the source has not been modified. Artifex is very explicit about their intention on the licensing page of their website.

It depends on the definition of “modification” and “derivative work”. Artifex is adamant that any software using Ghostscript is a derivative work, and the copyleft will apply, so all of your source code must also be released under the AGPL license. This is especially true if your software cannot function without Ghostscript.

If you are only distributing your application (i.e. not a SaaS app), then you could make Ghostscript an optional plugin that people can manually install (like LAME for Audacity.) But a SaaS app provides access to the application over the network, so you cannot use Ghostscript without a commercial license, or without releasing your application’s source code.

I didn’t see anything about Hancom modifying the Ghostscript source. It was the fact that they distributed Ghostscript along with their own application, and their application depended on Ghostscript for some functionality. That was enough to trigger the GPL copyleft, so they were violating the terms of the license and had to settle out of court. The AGPL means that you would be violating the license by providing access to your app over a network.

Nobody is suggesting that an AGPL licence violation would result in a criminal penalty, but if you got caught you may be forced to release any changes you made to the source code. And you could lose the ability to use the software in future—if your business relied on it you might be screwed.

Personally I think the AGPL is stupid, but people are free to pick whatever license terms they like for their copyrighted works. Whether I like it or not is irrelevant.