There's a web-design philosophy known as Progressive Enhancement which is one you should consider. The idea is you build a basic site that is usable and workable, and then you layer onto this enhancements like jQuery and browser-specific stuff to "enhance" it. This way you get a site that works for everybody and looks nice for the majority.
If that doesn't convince you, then consider other reasons for having a site work without javascript:
It is more SEO friendly. If your site relies on JS for content and links then chances are search-engines will be ignoring large chunks of it.
Imagine you are an eCommerce site selling widgets. Now, even if only 5% of your customers disable javascript, that is a potential sales loss of 5%. Is it worth losing customers over?
Don't discriminate against the disabled. Relying on javascript means your site is not accessible and, in some cases (such as government/public sector sites), you could be breaking the law by discriminating against people.
