I think the implicit criticism is that it is not suited for similar real life problems, because you never know if you have some problem for which it is well suited or some nearby problem for which it's not until after the fact.

This is surely true, but I think as criticism it misses the mark because nobody seeing a problem of similar complexity to GoL should say "I know! Let's write a one-liner in APL!" The fact that it's possible at all is what is impressive.

It's a little like if someone wrote a post criticising Ruby on Rails by writing a game engine in it, and then pointing out that it's slow.