The point of creating adaptive sites is to create functional (and hopefully optimal) user experiences for a growing number of web-enabled devices and contexts. It’s not because it’s “the right thing to do”. It’s not because it’s fun. It’s not because it’s trendy. It’s not so you can impress your boss by resizing a browser window.

In order to deal with all this diversity, we can no longer just cross our fingers and hope that these devices’ browsers are capable enough to properly render desktop designs. We need to actively take matters into our own hands and do all we can to create more contextually-aware, flexible experiences. The desktop-only days are gone. And yes, addressing this involves adapting layouts, but it also involves addressing a ton of other stuff.

Brad Frost — Responsive Web Design: Missing the Point