I'm sure I'm not a good representative Lisping example, but I routinely use let to bind more than one variable, especially when extracting program state from a URL in multiple variables, and probably use the implicit progn in cond 70% of the time. I can see the value of not allowing the implicit progn which would force creating more numerous and smaller functions, but in the case where I have only 2 expressions in a cond, a function just for that would seem a bit verbose. But again, this is really no big deal as with ARC, one can write a macro utility to put the multiple option back in.