Sometimes important Windows Updates are unchecked by default

Jskid

TS Guru
I've noticed on a few systems in Windows Updates some important updates are unchecked by default, for example Internet Explorer 10 For Windows 7 x64-based systems and various updates for the Microsoft .NET Framework 3.5.1 on Windows 7. Why is this and should I still install them? Why would they be important but not installed by default?
 

St1ckM4n

TS Evangelist
Depends on what your Windows Update settings are like. Mine is set to "notify" only, and every since update is unchecked by default.

.NET framework is kinda like a software that is required for other software to run ... e.g. "iOS v5 or higher is required to download and install Instagram on your iPhone"