>When reading other people's code you now effectively have to learn what "language" they use too

And? This is true of code in languages without macros, too. You have too learn all the vocabulary, all the types they use, all the functions, all the structure of the program— macros are just a tool for taking these domain-specific things and packing them into a denser syntactic abstraction. A well-written macro improves readability in both the short and long terms.

I mean, say I write a couple of macros to deal with a database and I write code like

    (with-sql-connection ("localhost" ...)
      (select *
         from  "customers"
         where (= "lastname" "Smith")))

Do you really think that's less readable than the nonsense you'd have to write a typical "framework," or worse, building the command string by hand?