Toki Pona is an interesting conlang for me, less due to its potential role as auxiliary language and more due to how much it highlights that linguistic communication is intrinsically complex - and trying to reduce the complexity in one system will inevitably lead to an increase of complexity elsewhere.

And in Toki Pona's case this means that you aren't memorising just the 123 words, but also a bunch of fixed expressions to refer to things without a word of its own. Such as:

• "toki pona" good language - the name of the language. No, we aren't talking about your favourite language, unless it happens to be Toki Pona.
• "telo nasa" beverage intoxicating - alcohol as a substance, or booze in general.
• "sike tenpo" round time - year. "round" contextually referring to the Earth around the Sun, not e.g. the Moon around the Earth. etc.

You can disambiguate those, sure. Language (as a human faculty) offers you resources for that. But you're going to decrease the information ratio, or you'll need to rely far more on the context, potentially not available for the hearer/reader. And once you take things like this into account, the net result isn't meaningfully more or less complex than a natural language, it's roughly on the same level.