LLM Indexing SDKs
A non-obvious benefit of publishing SDKs is that LLMs can index your public code and teach others how to use your API. Without SDKs, there's no public code for LLMs to learn from.
I just searched one of our customers (https://magichour.ai/) on google and saw this from Gemini. (Although in typical LLM fashion, it'll confidently show people an installation command with a typo in it):

Sideko Releases C# SDK Generator
Sideko's new C# SDK generator, leveraging C#'s growth (+1.43% in TIOBE), creates invisible, fully tested, strongly typed, and auto-authenticated SDKs with customizable code and complete documentation.
The Stripe API Challenge: How Sideko Generated over 1 Million Lines of SDK Code in less than 60 seconds.
Sideko's Rust-based SDK generator created massive Python (~607k lines) and TypeScript (~421k lines) Stripe SDKs in under 60 seconds on a 1GB container, saving an estimated 9 engineer-years of development time.