A series of recent, influential design books and articles have convinced the web's designers to go for grey-on-white type, despite the fact that many people can't read low-contrast type (and it's even worse on mobile devices, which are often read in very bright sun, on screens that have been dimmed to save battery)
Ironically, these design guides — The Typography Handbook, this article by Adam Schwartz, and others — warn that designers should beware of reducing the contrast, but designers, seated before giant, well-calibrated monitors in well-lit offices, took their advice as permission to dial contrast down to illegibility for people with poor low-contrast vision.
I'm one of those people, for the record. I use a browser extension to let me turn grey type black (alas, the plugin defaults to white on black type, which I also can't read very well, and requires a lot of clicking to get to black-on-white), without which many sites would be literally unreadable for me.
Kevin Marks, who ran down the trend's origins, makes an excellent case for why grey type is bad news, and offers an alternative idea:
When you build a site and ignore what happens afterwards — when the values entered in code are translated into brightness and contrast depending on the settings of a physical screen — you're avoiding the experience that you create. And when you design in perfect settings, with big, contrast-rich monitors, you blind yourself to users. To arbitrarily throw away contrast based on a fashion that "looks good on my perfect screen in my perfectly lit office" is abdicating designers' responsibilities to the very people for whom they are designing.
My plea to designers and software engineers: Ignore the fads and go back to the typographic principles of print — keep your type black, and vary weight and font instead of grayness. You'll be making things better for people who read on smaller, dimmer screens, even if their eyes aren't aging like mine. It may not be trendy, but it's time to consider who is being left out by the web's aesthetic.
How the Web Became Unreadable