The idea that you can write a useful program in Lisp faster than in other languages is pretty unsupportable. For most users, the time and effort spent getting Lisp up-and-running on their machine of choice will already have lost. Incidentally, I played with the interactive REPL and it wouldn't advance beyond the second page.
And, if you do write a useful program in Lisp, you run into the deployment problem. The deployment problem is pretty bad. Apple's Advanced Technology Group at one point had one of the highest concentrations of Lisp-heads in the world and produced a bunch of stuff like Dylan, Sk8, etc. that was intimately tied to their Lisp implementation. Not only was this not cross-platform, and pretty hard to distribute and deploy even on the platform it was created for (680x0 Macs) it was killed by the transition to PowerPC.
This isn't as big a problem if you're writing server software, but it's absolutely disastrous if you're writing desktop or mobile software.
One could show someone how to do something useful and deployable in Python, PHP, Perl, Javascript, or whatever in a few minutes and chances are they could have a usable dev environment set up in a few minutes.