Kevin Marks has a surprisingly quantitative take about why the web is getting harder to read:
There’s a widespread movement in design circles to reduce the contrast between text and background, making type harder to read. Apple is guilty. Google is, too. So is Twitter.
Typography may not seem like a crucial design element, but it is.
The key takeaway: blindly following design trends can make it harder for people to read your stuff. That’s especially important for fundraisers, who often deal with older audiences.
Fortunately, you don’t need to adopt a design because it’s trendy. You can experiment to find out if that design better achieves your goals than what you’re using now.