Why do you set styles via javascript?

Just curious why you set inline styles via javascript.

Causing a couple of problems when I try to customize it. For example:
what if I don’t want to use a hexcode for a colour value?
Why is there a default border on thumbnails.
What if I don’t want to use pixels for width/height?

http://ww.wp.xz.cn/extend/plugins/image-gallery-reloaded/