There's an informative talk by Alice Bartlett, a front-end developer at gov.uk (the UK government digital service) on Youtube. In the presentation, she states that two of the requirements for gov.uk are

  1. Functional without Javascript
  2. Functional in IE7+

Link to the relevant part of the talk: http://youtu.be/CUkMCQR4TpY?t=17m34s

And also http://youtu.be/CUkMCQR4TpY?t=19m21s

The essential point made is that for much of gov.uk, it isn't that difficult to make the site work without Javascript or work in IE7 either.

Purley personal opinion, but web design has become incredibly bloated with so much cruft added to web pages - be it unnecesary Javascript or excess CSS. Web developers pick the tools that make their lives easier (as you'd expect), but that doesn't always mean that users get the best experience.