So, probably one of the most dangerous things you can do (opening the door to rootkits and an infected BIOS) doesn't take just a click and an undistinguished warning dialog? Also, this has been around since at least Windows 7, its not evidence of us sliding down a slope.
Yes, rebooting Windows one time to do it isn't that bad, but it's a start. I won't be surprised if the next version of Windows (next after Win10) removed that feature completely.
Forcing users to run only signed drivers is a problem because only Trusted Vendors can get proper certification (after paying proper amount of $$ to Trusted Certification Providers). Such restriction will basically kill hardware tinkering, which is one of the goals of the War on General-Purpose Computing.
[0] - It's not really "coming" anymore.