But I confess that being able to post a new entry to an API and have it published instantly sure is attractive. If WordPress had a better security track record, I’d be tempted to switch to it. You don’t get much more secure than a bunch of static files served straight from disk, though.
A lot of people use WordPress for drag'n drop site building. Getting such sites over on Sqlite would increase uptime (less chance of failure withou the separate DB server), reduce support load (easier to move from other providers) and so on.
Alas, compatibility will not be that great with various plugins, so I fear adding SQLite this late will just have the opposite effect.
PHP isn’t natively supported there yet, but I can imagine such a thing could be built and be successful.