[bmf]

Richard Gabriel did a great write-up of the trade-offs during the ANSI Common Lisp standardization process:

http://www.nhplace.com/kent/Papers/Technical-Issues.html

What I took away from it was that macros get more tricky to write when you have possible variable capture for functions, which we humans seem to be a little more blind to than for values.

Item 18 contains the compatibility concerns for existing code, which the guys writing the standard seemed to think critical to keep the various vendors on board.