Currently the state of implementations like SBCL and CCL is really good. There are lots of further improvements possible and necessary as the computing landscape evolves. But from a Lisp user perspective, the free implementations have never been better than today. Users should be aware of that and take advantage of that. More work on graphics, development tools, etc. is welcome, though.
I understand that Clozure CL and SBCL are also good. Maybe not THAT good, but good. Thing that bothers me with that argument is if CL or Lisp in general had the appeal to the critical mass of programmers, it would be built - no matter if standards were the obstacle or commercial implementations. They would come and build a new one, no?
As for the libraries - there surely is a way to make bindings to other libraries. For example, we have that kind of problem in D, but we can easily bind to C libraries, so that is not that much of a hassle.
My deep thought on all of that is what bothers me the most. Here is my theory. Is it possible that the real reason is that there are basically two types of programmers:
1. Recipe / Cargo Cult programmers that are programmers by career inertia
2. Programmers that think more about the nature of the problem and hack their mindset to the code. You know, the type that thinks more than they code - code is just a splurt at the end of the process.
If that is true, and if Lisp appeals only to the second bunch (not all of them, of course). It might be a hypothetical disastrous indicator of the ratio in programmer population.
Or maybe I'm just thinking too much about it all.
1. because I seem avoid so much code that I could see myself having to write in other languages, and
2. because it gives me all this great dynamic functionality while still being extremely fast, especially compared to other languages.
Once I realized all the crazy things you can do with it and still run fast its been difficult to imagine using anything else where I have a choice.
This assumes lisp = Common Lisp.
Clojure for example is entirely Open Source and a delight to code in.