Why do you have to shutdown you computer properly? Why shouldn't you push the power button for 5 seconds?
Well, we all know that turning off electronics are pretty simple, you rotate the key or flip the switches but for some reasons turning off your computer is a complicated ordeal, I mean, it isn't difficult to click on the Start icon at the bottom right corner of your screen then select shutdown or just tap the button on your chassis but instead of turn off instantly your PC will always go through this kind of rigmarole that can last for minutes before it finally powers down.
Hold on, why can't I just push down the power button for 5 seconds or flip the switch at the back of a desktop for instance shutdown?
Let me just surprise you, you see when you click on that shutdown button, your computer goes through a series of steps that are primarily design to protect your data. Killing your computer abruptly while you have unsaved works means that those works are probably gone for good. Even though some modern days programs have autosave features, but they don't always work. So one of the delays you might encounter is your PC prompting you to save anything you have open.
There are also less evidence things going on in the background, chief among this is that your Operating system send some signals to running programs that it's time to power down, so it tell this programs to wrap up whatever it is they are doing. This is important because this programs may be in the middle of writing data to your disk . And this can be anything from program update to file download to a registry key been modified. There is a very common thing here, you are on a very risk of data corruption if you just power off your computer without warning. The half written data, written by any program or OS itself on your hard disk before you shutdown your computer without warning might not be anything your computer can use.
And because the ways some computer drives and file system work, you might not only corrupt whatever data it is been written at the time of power down, you might also damage other files that are in a cache or a nearby physical location on your drives.
Fortunately, the file system used by modern versions of windows called New Technology File System (NTFS) has a feature called journaling. That means it keeps a log of data changes to reduce the risk of corruption. However, problems can still occur if you don't shut your computer down properly, hence the disk check messages that you sometime get when you power your system back on after power outage or similar.
Bringing us to one of the biggest reason that users force a system reset.
SYSTEM UPDATE
System Update that seems to take an eternity that you just need to wrap up some work and go to sleep, well there is a reason that your PC explicitly tells you not to turn off the power. During a typical power loss or sudden shutdown, you're likely to loose a little bit of unsaved work but turning off your PC during an update can result into a problem that can prevent your PC from even booting up,
such as Corrupted half written registry files or system files, I will even suggest plugging your computer into a UPS or making sure you have a fully charged laptop battery during update isn't a bad idea.
CONCLUSION
Basically the more of the story is that unless your computer is hopelessly frozen and you have no choice but to completely kill the power make sure you turn your system off properly, it may take little more the but trust me it's a lot easier to have to reinstall windows.