Firefox and Safari each have a 'Reader Mode' which does exactly what you want: presenting a web-page in the absence of any web design.

It's really the ultimate condemnation of modern web design that this feature is so useful.

Edit: won't help the data-consumption though, as I believe it can only be enabled after the page has loaded

In reply to your edit. You can use something like umatrix to block almost everything (even css) and reader mode will still work, I do this for most newspapers and works quite well.