Why? Hierarchical design may be hard to follow and read. It adds additional work and it can bring in unnecessary mistakes.
Why? This helps you to minimize number of revisions of your board.
Why? You will quickly find the page which you would like to open.
Why? People still do the best job.
Why? The price is almost the same and you do not need to stock both. Also, it may help with reliability and stability.
Why? Cheap, easy and works. You may need some practicing.
Why? One wrongly placed tall component can increase the total height of the board.
Why? It is very hard to add something later.
Why? You need to be sure, that you are connecting signals with the same voltage levels. It also helps during debugging and schematic checking.
Why? It will speed up development process. You can always remove it later.
Why? Anyone can lose the data on hard drive. And it can happen anytime …
Why? You may not want to place it in the middle of the board where all the currents and signals are running.
Why? Everyone reading your schematic will know how accurate it is and if they should report you any possible mistakes.
Why? If you do not follow VIA ratio recommendations, it may not be possible to manufacture your PCB.
Why? You want to clearly see from schematic where each pin is connected. It's very important when checking schematic and connections.