Natural languages are the way they are because of two factors: (i) the inner structure of the human brain, which grants a considerable degree similarity across languages; and (ii) spontaneous order, which enable them to better fit the needs of the speakers, giving rise to idiosyncrasies. Artificial languages are “centrally planned” by a designer who thinks he understands how a language should be in order to meet its purposes (but he doesn’t). Needless to say, it’s the designer himself who establishes such purposes, not leaving this task up to the speakers who will ultimately use the language. By the way, Esperanto is *NOT* nearly as well designed as many people think it is. Its grammar contains many “gaps”, many parts that are underspecified. So, Esperanto speakers, even if unconsciously, end up filling those gaps with chunks of grammar coming from languages they already speak. So, what’s the result? Many different dialects of Esperanto! Yes, that’s it. And this goes against the very goal of Esperanto’s designer of having one uniform language for the whole planet. It must be said that Esperanto was not even meant to be “more logical” than any language, neither was it built totally from scratch. There are literally hundreds of artificial languages out there, all of which are failures, and some of them aimed at being more logical and were built from scratch. Esperanto was meant to be more regular (which is not the same as more logical) and was built from adapting pieces of various existing languages. The goal was to have a politically neutral language; not as a way of replacing all languages, but as a way of having one single language which would be everyone’s second language. According to the central planner, everyone would be equally proficient in this second language. What happens in reality? Well, two things. First, most people don’t give a damn about this and go learn English as a second language because, let’s say, they value “understanding Beatles lyrics” higher than “speaking the language of world peace” (maybe they go lean Hebrew instead, because they want to know every part of the Talmud by heart). Second, many Esperanto aficionados end up having kids and speaking only Esperanto with them. In the end, those kids turn into “native speakers of Esperanto”. The “unintended consequence” of this (to stick to a hayekian terminology) is that those kids, from early on, end up “filling the gaps” of Esperanto grammar by themselves, giving rise to dialects. And those dialects are super solidly built and immutable for those speakers (for whom French/Japanese,etc will be a second language), and yet not exactly as planned by the designer. For more information, I recommend the book “In the Land of Invented Languages” by Arika Okrent (2009).