I have always been a big supporter of keeping system images through the Windows install process as well as before doing any updates. Windows system updates for example can occasionally go bad. Installing new software is always risky (ILOK...). Occasionally everything goes well but the new software is buggy or has a bug that you are not going to live with. Imaging is the easiest way to keep safety backups of your system.
When was the last time you created a backup of your system that would allow you to restore back to its current state in a matter of minutes?
If you are well organised you might have this all under control but I would bet the farm on the majority of people do not have this in hand and only occasionally create backups or even forget until its way too late and the damage is done.