Note: the first comment in the blog post you liked has the exact same complaint as in this thread. It's amazing how people start complaining before consulting the manual. As if all software in the world should be obvious by looking at icons and buttons. And yet it isn't. I am looking at you, Microsoft Ribbon.
This is a very old argument. However, there are only so many hours in a day. I use Gimp occasionally but I bought Photoshop because there are more tutorials, blogs, and resources in general. I'm a developer and weekend warrior with graphics. If the apps are too different, I only have time to learn one.
For Gimp to really hit the main stream, it should make it trivial to switch between it and Photoshop.