Its like rearranging small things according to my needs.
My PC should work and feel like my unique taste, not just any other PC.
Have you ever seen a custom made bike or car? Its exactly like that.
Windows allows us certain degree of customisation and leaves room for advanced users to Tweak things here and there. I am not destroying the Op sys to shreds, just redecorating it. Example: Some softwares keep tack of our activities by default. I hack into it's registry and change the default itself. Problem solved!
In fact all open source softwares expect us to change things. (Windows is not open source, by the way) Bill Gates is a very protective man!