[comex]

Luckily, HTTP only requires the browser (which tend to be frequently updated) and server to be upgraded, not some random aging routers, there is little reason to fear adoption, there is minimal harm in keeping both protocols around for some time, and there is something much closer to a "must have" feature - speed.

[ryanpetrich]

A lot of hardware (proxies, DPI gear, hotel wifi hotspots, cellular carriers, etc) sniffs/mangles HTTP in transit and must be verified to be compatible with new HTTP features. HTTPS doesn't have this constraint.

[nl]

Browsers are frequently updated only since Google moved the game on with Chrome auto-update.