It is surprising how bookmarklet creators tend to ignore built-in browser features, like disabling css :)

A similar tool that I use for assessing accessibility is:
http://wave.webaim.org/toolbar

- Accessibility features and errors are highlighted
- Can view in text only mode
- Can view in headers only mode
- Can view the structure/order of elements to see how a screen reader would read them

Removing CSS is just one of many dozens of things that a web developer needs to be able to do.

There are really good tools available for the purpose, such as the Firefox add-on "Web Developer". At a click (on a toolbar, or a right-click on the page if you don't want a toolbar) you can not only remove CSS, but you can edit the CSS on the live page.

You can also do all kinds of things with: the cache, Java, JavaScript, redirects, fonts, colors, popups, proxies, referrers, cookies, styles, browsers, forms, images, "alt" attributes, shortcut keys, anchors, blocks, tables, meta tags, HTTP headers, the document object model, history, authentication, measurement, comments, hidden elements, frames, links, mobile versions of the page, screen size, heading heirarchy, deprecated elements, validation (css, accessibility, html, feeds), errors, html source, page parameters and much more.

It's a one-time install of a polished toolkit, which would need dozens of individual hacks to replicate its utility.

Not everyone wants to install browser add-ons, fair enough, but to develop web pages without a tool like Web Developer is doing things the hard way.

https://addons.mozilla.org/en-US/firefox/addon/60

Built-in feature in most modern browsers.

Firefox 3: View > Page Style > No Style
IE8: Page Menu > Style > No Style
Opera 9: View > Style > User Mode

Chrome does not support it, that't the reason for this feature. I got it under home icon (with some other features) for several months