If I were you I'd look at it from the Lisp tradition: as part of a 50 year history with many dialects, rather than as an urgent effort to manage one particular implementation consisting of a huge pile of libraries on top of a badly designed language core.
People who want languages like that already have plenty of options, even Lisp dialects.
I didn't mean to say that core language isn't important. It is important. My main point point is that the community should be able to partecipate in the design. This is why I've advocated a fork of Arc, because to improve the core of the language you need help from who will use the language. A prototype is a good way to make this happen even when you're in the design phase and not in the production phase, but it is useless without a communication channel between the designer and the users.
1. The time scale. I don't want to make what people think they want right now. Following that recipe earlier would have got me Perl, which lost its lead to the language I would have gotten a little later, Python, which lost its lead to the language I would have gotten a little later, Ruby, which... See the pattern?
2. The audience. "Make something people want" is a recipe for companies. Their goal is to make a lot of money, which means aiming for a wide audience. That shouldn't necessarily be one's goal in every kind of work. It's ok to want to be Jane Austen instead of Perez Hilton, even though Perez Hilton is what most people want.