A more pertinent point is that if your website doesn't really need JavaScript, and most don't, then it will be faster, more reliable and require less maintenance if you simply don't use it. There are also security risks if you depend on a huge tree of JavaScript libraries from unidentified people.
I've lost count of the number of times I have been unable to buy something online because JavaScript bugs or incompatibilities prevented me from completing the purchase. (It's probably about two or three times. I'm bad at counting, OK?)
One word: accessibility. Nope? Very well, carry on. (The remark "that's your own fault for using a screenreader [i.e. text browser]" is needlessly flippant, though.)
I've lost count of the number of times I have been unable to buy something online because JavaScript bugs or incompatibilities prevented me from completing the purchase. (It's probably about two or three times. I'm bad at counting, OK?)