That is like saying that I must make sure my programs work for people who don't have a computer and rely on anotated screenshots being sent back and forth. To my programmer brain, that is just stupid.
It is one thing if we were talking about a webpage ala 1995 for joes autoshop. At most it will have a comment field (or, the horror, a guestbook) and each url will map logically to a specific public part of the site. Most likely there will be no concept of users at all.
The same thing goes for a blog although you won't get the auto updating twitter feed and, if the blog uses diques, you may have to click a couple of links to see them.
But a webapp is more like Google writer. It just lose all meaning to make it work without Javascript.
Accessibility cuts both ways, though. Choosing to prioritize the HTML-only version decreases accessibility to people who have limited bandwidth or download speeds.
This surely hasn't been a major problem since probably the 14.4k modem stages for typical sites, and, even if it was, wouldn't limit accessibility (except in the sense that it'd delay viewing by a few milliseconds->seconds). Especially when the majority of the bandwidth cost will be data that has to be sent regardless (maybe with a necessarily increased amount of metadata).
Edit: Graceful degradation should be a tenet of web development. Having no provision for a person who doesn't have javascript enabled seems bizarre to me, and being bullish about the requirement seems even more bizarre...maybe i'm just getting cranky with age or something.