He mentions "true to browser type rendering" multiple times, which basically means "shitty type rendering." Browsers, at worst IE and followed closely by Firefox, are horribly bad at performing proper antialiasing for some reason. (The only exception to this rule is Safari, which does a decent job.)
I don't think we should bring the ridiculous shortcomings of browsers backwards into our design/mockup apps. I think we should continue designing stuff in a way that doesn't force us to conform to the lowest common denominator. Sure the depictions we might see in design apps are not strictly "accurate", but I don't have problems watching the graceful degradation of my designs through the various browsers.
It's the browsers that need improved type/graphics rendering, the not mockup/design applications that need to bow down to them.
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Finally, I don't know if it's actually a good idea to create a web-focused design app yet. We're still in the very early days of the web, and I don't think the long term conventions and standards are in place yet. We're in the flux. The blank, non-assuming canvases in Photoshop and Illustrator are good for fostering new ideas and pushing forward the state of art on the web.
That those apps weren't designed strictly for the web might end up being a net positive, especially as we go into the future and define what the web will look like in the long term.