Performance is important
My benchmarks show that guile is a pretty slow. For example, on one machine, it was 238 times slower than C. So, instead of a 3.6 GIPS machine, we'll all go back to 15 MIPS. Who here wants to use a 486/66 again? Who here isn't old enough to remember when Intel had numbers for chip models? Perhaps the long jump support could be removed and half way decent performance could be put in. I mean, what good is a functional language when it's faster when you code loops?
I was researching LISP a couple years back and ran into a great quote. It talked about how a student had written an elegant matrix multiply function in LISP, which had the misfeature of being incredibly slow. It caught my attention because i'd written a nearly identical function, and was amazed at how poorly it performed. The author made the comment that no C programmer could make such a mistake. However, he totally failed to give the slightest hint on why the performance should have sucked. And, he continued to rant about how (compiled) LISP was as fast as C.
Readability is important
That said. I know dozens of languages. I understand my 30 year old BASIC programs without much effort. I was a bit more clever with my 25 year old C programs, so they're a bit tougher. LISP is one of only two languages where i actually took a class. But none of my LISP or scheme is halfway comprehensible two weeks after i've written it. Forth is a bit better, taking a couple months. Procedural languages are simply easier. At the end of the day, you spend most of your time in maintenance. If it isn't broken, then the requirements are changing. Oh, and time is money, just like Einstein said.