Thanks to Dan, Arika Okrent answered a question on toki pona.
Q. Is it preferable for a language (invented or non) to have a relatively small vocabulary? For example, an invented language by the name of “Toki Pona” consists of only 118 words. This makes it harder to communicate with the language alone, and demands the people using the language strive to share/understand context. A language with a larger vocabulary requires less shared context, as words can be more precise/cut loose from non-verbal contextual ties. — Dan
Arika Okrent: You’ve pretty much answered your own question here. A large vocabulary is harder to learn, but requires less reliance on other strategies for making meaning. A small vocabulary is easier to learn, but requires a lot of support from context or established conventions. Generally, more simplicity means less precision and more precision means harder to learn or less flexible. Natural languages strike a good balance between flexibility and precision, and if you want your invented language to serve for the range of functions natural languages do, you need ways to provide for both.