[plt-scheme] Comments on an alternate syntax for let?

Grant Rettke wrote:
> In the comp.lang.lisp post [The syntax of LET] by Jeff M, hed wondered
> why the syntax of let wasn't simpler, like; (let (x 0 y 1 z 2) (+ x y
> z)). Someone proposed he write a macro.
>   

What is the the advantage of

(let ((x 0)(y 1)(z 2)) ...)

over

(let ()
    (define x 0)
    (define y 1)
    (define z 2)
    ...)

except that simultaneus evaluation in the first case? What we can not do 
with second and we can with first?