I think it's probably a matter of taste, and also the type of project (which surely are correlated). I prefer this sort of micro-framework because it gives me control. I like my software to consist of many independent pieces that I can mix & match and then string together. The Rails approach is more the opposite, you've got the structure and fill in the gaps.

Admittedly, none of my web projects in recent years have been typical database-backed web apps. Clojure (and thus Compojure) is actually a fantastic candidate if you're keeping state in memory - STM is made for this.

On my infinite TODO list I've got an xLightweb back-end for Compojure. This would allow asynchronous I/O in the style of Node.js, something that's a bit tedious in pure Java (no closures), and Clojure has certain advantages over JavaScript/V8. I find asynchronous I/O hard to imagine in a Rails-style environment.