CMS Creating a new template for widget use - Create plugin??

[محروم.كوم]

I've created a couple of templates that reference some css that I've put in additional, and it works fine for me. However, I was given an impression by a number of posts that many take the step of creating and activating a plugin with php code similar to this:

Code:
$myusername = $vbulletin->userinfo['username'];

vB_Template:reRegister('vbcms_my_custom_widget_t emplate',array('myusername' => $myusername));
It doesn't appear that this is a necessary requirement to use custom templates for widgets, but I'm curious about why some perform this step? My only speculation is that this step is necessary if one were to desire using raw variables and such in their template??? __DEFINE_LIKE_SHARE__