From a first principles perspective, it's me and the computer, and I want the computer to do something. My laptop has the following input devices: keyboard, mouse, webcam, and microphone.

I mostly use the keyboard and mouse. There are some places where the mouse is better than the keyboard. I was playing online chess today, and I like to drag and drop the pieces. It feels more natural and not that much slower than inputting the coordinates.

But when I was coding today, I needed to navigate through my code quickly. The mouse would have been much slower than vim's CTRL-D, CTRL-U, and /search_keyword, so I used the keyboard.

For the non-professional programmers, Project Bloks might be more like chess's drag and drop. It's more natural and not that much slower for simple tasks. I can see why non-professional programmers may like it.