Most people don't particularly care how things look, so long as they're reasonably familiar, well-ordered, visually inoffensive, and functional. After that, it's optimizing for performance metrics and ensuring that the client is happy with the aesthetic of the final product.
Client usually wants to emulate some elements of the latest aesthetic trend. Can't blame designers for what's ultimately a fashion trend. Especially when breaking from the trends and convention put you at risk of looking dated or driving away consumers.
It's more that, I've read critics of modern web design. And while I can understand that some people don't like it (myself included for some things), the visceral hatred that some people have in their rants against it is so great, I can't possibly send that to a client with a straight face. It's so extreme it's absolutely useless.
Edit: At some point, while you can agree with some of the critics' points, they become completely out-of-touch with reality and the typical user.
Client usually wants to emulate some elements of the latest aesthetic trend. Can't blame designers for what's ultimately a fashion trend. Especially when breaking from the trends and convention put you at risk of looking dated or driving away consumers.
Edit: some grammar