Allow me to suggest a few possible courses of action you might take:
1) Make a better one. 50 years in isn't too late and the data is there.
2) Introduce a modicum of specificity into your critique.
I understood it to show a small subset of languages primarily in Europe, clearly marked by contrasting colours. You clearly disagree that this is valid, and you may be right, but saying ~"this map isn't another map" and ~"this map sucks" doesn't add anything to the conversation.
1) It depends. If the author indicated a specific goal and didn't reach it because they didn't go into more detail in one area, then I'd say something along the lines of "I got the sense that the author's goal was to try and convey x, but didn't seem to fully reach it. More time was spent on y, which could have allowed her to flesh out more detail in the backstory of x". Otherwise, if it were their goal to discuss the geo-political exchange of Greenland between Scandinavian countries, I probably wouldn't remark on the exclusion of India from the discussion as a detractor from the quality of the literature. If the latter is the approach a book or movie reviewer took, I'd critically evaluate their review. Not that the remark wouldn't have value, but it would have much more value in an addendum, feature request, or new creation.
1a) My problem is not pointing out flaws — if they were truly obvious, they wouldn't need to be pointed out —, but in the potential value derived from the critique. The exercise in explaining how something could be done better increases the robusticity of the answer. For example, you could say "the colour scheme is unintuitive" or "the colour scheme might be difficult to process for red-green colour-blind people. It might be better to do x". Especially if you consider a subject that is obvious to you but not someone else, more detail would help.
2) I'm not trying to personally attack you, would likely agree with your sentiment, and didn't suggest that you literally said the map sucks. Simply that saying something has a subjective trait, when communicated as objective, doesn't produce much value in my opinion.
1) Make a better one. 50 years in isn't too late and the data is there. 2) Introduce a modicum of specificity into your critique.
I understood it to show a small subset of languages primarily in Europe, clearly marked by contrasting colours. You clearly disagree that this is valid, and you may be right, but saying ~"this map isn't another map" and ~"this map sucks" doesn't add anything to the conversation.