Maybe this easy way should be documented in the wiki / official install guide.
The USB/HD Install has been in Tiny Core for some time. However, in Tinycore 3.6rc1, 2 and 3, additional features have been added, making it much more versitile. An improvement has even been made in rc3 which was not in 1 or 2. I have requested yet another improvement, but I am not sure if it will be implemented. So this is very new, and still being improved. These improvements will not be official until Tiny Core 3.6 is released.
When 3.6 is released, I agree, it should be documented in the wiki / official installation guide.
I believe the pages of the other methods of installation should be kept, so people also have those options.
I hope to have time to make a contribution.
There probably needs to be at least 2 pages, one using the installer while connected to the internet, where installing apps is easy, and one using the installer without being connected to the internet, where apps need to be installed manually.
I am not sure if the team wants some of this in the official installation guide.
Keep your eyes on the wiki in the not too distant future for these additions.