[tialaramex]

As well as the affirmatively "insecure" marking in the URL bar for unencrypted HTTP, it's not a Secure Context (except localhost) and so modern browsers don't offer any new features for this case.

If you're writing an HTML 4.0 web page that's no issue. If you were building a video chat, or you were going to add geolocation to your "Where's my closest store?" page or you want to send Notifications, or you've got a framework that needs Service Workers, those APIs are Secure Context only and won't exist.

The general rule of thumb is, if you could polyfill it, then it's available even without Secure Context, otherwise you need Secure Context to get the new feature. Some older features are being retrospectively given this treatment.