That's simply to give web developers another incentive to use TLS. There is no real technical reason beyond that.
>any resource, even an image, being loaded from an insecure endpoint results in a warning
By nessesity, unsecured resources undermine TLS's integrity guarantees. An unsecured image on my bank's website would mean that anyone who MitMs my connection can swap that image to show a message that appears to be from my bank.
The internet is no longer the trustworthy place it was in the eighties. HTTP2 is one attempt to make developers catch up with ye that.
>any resource, even an image, being loaded from an insecure endpoint results in a warning
By nessesity, unsecured resources undermine TLS's integrity guarantees. An unsecured image on my bank's website would mean that anyone who MitMs my connection can swap that image to show a message that appears to be from my bank.
The internet is no longer the trustworthy place it was in the eighties. HTTP2 is one attempt to make developers catch up with ye that.