kulupu Linku’s 2022 survey demonstrated that meli and mije are less used than all the rest of the nimi pu, being intentionally used less frequently than pu itself! tonsi, even despite its popularity, lags further behind that.
These words are in an interesting place in Toki Pona’s list of concepts. Toki Pona doesn’t value ruthless minimalism- there are many compromises between having fewer words and making the language easier to understand! But even in the core pu vocabulary, some words have little expressive power and are hard to extend into new definitions. meli, mije, and tonsi fall into that category- which is one of the common complaints leading to speakers not using these words.
One of the earliest lessons new speakers learn is to finding a balance between provided detail and brief, parseable statements. In this process, learners discover that the highly precise detail that marked their initial learning is no longer necessary! But at the same time, this also means discovering that some words’ expressive power is different from others’.
Gender is an important concept for self expression, but distinguishing people and things by their gender becomes less important as you learn what details most quickly and effectively communicate what you’re thinking. As such, even for those who still use these words, they end up being very rarely used. Toki Pona’s gender terminology is stuck almost exclusively in self-expression- and while that is important, Toki Pona is already a part of self-expression, allowing you to choose your own head noun for example.
What if we extended meli en mije en tonsi into more meanings? I have personally seen some nasin co-opt the words to convey the difference in plugs versus ports, normally referred to as male and female components of electrical systems. However, that nasin is considered comparative or metaphorical- the difference would be better expressed literally with palisa for plug and lupa for port. Otherwise, there are no natural extensions for meli en mije- as lipamanka puts it, their semantic space is dependent on what a speaking being tells you about themselves.
If these issues were not enough to consider removing the three from your vocabulary, there is one more common complaint about them which borders on social issues in discussion of sex and gender. While many Toki Pona speakers say these words exclusively refer to gender, others say these words refer to sex. This creates a divide, and a contention, between different speakers who use these words differently. This is not something that is solvable without prescriptivism, and the Toki Pona community looks down on and rejects prescriptivism. To this end, speakers have rejected the use of all three words to avoid the debate entirely.
Most importantly, meli, mije, and tonsi are redundant. If gender is about self-expression, and it is, then any words may be used to express your gender.
I believe meli, mije, and tonsi are important to Toki Pona, and will remain- but I also expect they will be used even less over time.