I agree that it's not a problem, but for newcomers all that parenthesis accumulation is quite problematic. I speak out of my personal experience: I've abandoned lisp even before learning something about macros because I couln't stand the parenthesis. I gave a second chance to Lisp some time ago, years after my first attempt. I've walked through Seibel's book entirely and know I love Lisp, but the parenthesis give a really bad first impression, they only make sense after you get to know the language better.