I was also disappointed, but this decision seems reasonable to me. SQLite is still evolving, if you pick a specific version then you're stuck on that version or risk breaking people that depend on specifics of that version. Also a vulnerability anywhere in SQLite would expose billions of people to exploits. This is not the same as applications using sqlite internally, the web is a much hotter environment: most apps may expect potentially hostile input in SQL params, but with WebSQL everything is potentially hostile: the queries, the database files, even the schema may conspire under confusing concurrency conditions to corrupt the state of the sqlite engine to break out and exploit the user. Whatever you think you have to agree that this is a LOT of new surface area.

I much prefer this approach where the site brings their own sandboxed SQLite WASM package.