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GET has never been advertised to do anything except return () when
applied to something other than a LIST or a SYMBOL.  Thus your
charge of "language changes" is completely mis-applied.
    Date: 15 February 1981 11:39-EST
    From: Kent M. Pitman <KMP at MIT-MC>
    Subject:  GET of a HUNK
     ...[GET applied to HUNKs]
    It REALLY bugs me that these things aren't discussed in advance. I don't
    like this change and I would like it retracted. It is bad for two reasons:
     (1) It can break code. I haven't had time to analyze my packages to see
	.  .  .
     (2) It is not uniform with the treatment of non-user-hunks and the value 
	 of HUNKP elsewhere in Lisp. Please do not make changes to the language
	 which are not coherent with what little overall design philosophy 
	 there is still persisting in Maclisp after all the other changes that
	 have been forced upon it to get NIL going.
    .  .  .
Speaking of the value of HUNKP, the switch MAKHUNK also affects the
(now-obsolete) interpretation of hunks as pseudo-lists;  the default setting
of both of them is **not** to make this interpretation, and I don't really 
know of any current applications which change that.   If there were such
applications, then GET, GETL, and a host of other functions would have 
to be "refined".
   Incidentally, it was the development of NIL which discovered the
inconsistent behaviour of GET on hunks -- not, as you mistakenly suggest,
that MacLISP was changed to accommodate NIL.