timppu: I guess that's the problem in itself (and that it costs money). Not sure why, but many Linux distros seem to suggest turning secure boot off.
It cost 99$, once, not exactly the costliest of investment even for a small sized distro.
timppu: Also, doesn't it cause issues if you want to e.g. run installed Linux from an external USB device (e.g. a flash drive or USB hard disk)?
Depends of the "bios", if the UEFI support "legacy" boot options for CD/USB then will boot anything, even with secure boot enabled. All the UEFIs I have played until now (from cheap laptop to DELL servers) have the option, but again it's up to the manufacturer whenever or not the legacy boot option is be available.
timppu: It shouldn't be left to the manufacturer as many will get lazy and just drop the ability to disable it.
Maybe but how is it Microsoft responsibility ? If the manufacturer gets lazy they could also decide to remove the option to boot from an UBS key or on a CD or stop supporting UEFI incompatible OSes, it wouldn't be Ms fault either.
If Ms was forcing manufacturers to remove the option then I would agree that it would be a dick move, but here it's just them no longer making this option mandatory now that they no longer officially sell an OS not supporting secure boot (i.e. Windows 7)
timppu: At least there is no option to disable (nor enable) anywhere in the options anymore, or then they have made it very complicated how it is done.
Asus are usually pretty got a giving a lot of options in their bios, I doubt they would have removed this option, especially on a gaming laptop and even more on an older laptop. I suspect they probably just changed the layout of the menu and move this option somewhere else. Often it's either on the "boot" or "security" section.