You don't have to program directly in an AST to do metaprogramming. It's a trade-off: some people feel it's important to make metaprogramming as easy as possible, while others feel it's more important to have readable syntax.
Every Lisp dialect has some high-level syntax, e.g. quote, CL reader macros, and Arc ssyntax. These obscure the relationship between code and the underlying AST, but the designers felt that the gain in readability was worth it.
How much syntax should there be? A hard question, but I think it would be good for Lisp to move in the "more" direction. Readability is one of the big problems I have with Lisp, and macros, while certainly useful, make up only a small fraction of my code.
I'm so pissed that I upvoted you, now that I've seen your contributions to other threads. But hey, you managed to finally make a comment that didn't call someone gay or disparage gay people... maybe some positive reinforcement will help you grow up. Good job!
But yes, I can't for the life of me understand why someone would want to use TwinLisp.
And actually, SBCL is nearly as fast as C in many cases. So there's really no reason to not use CL, unless of course you don't like CL.