Originally Posted by Siosilvar
I was with you up until here. Just because they're willing doesn't mean they're going to forgo their saving throw. Admittedly, they're likely to, but it's not part of the rules definition of "willing", the use of "willingly" notwithstanding. "Willing" only means that you can cast spells restricted to willing targets only on them (or so the argument goes).
Being a willing target is a subset of the targets. You can enter that set in two ways 1) be voluntarily entering it or 2) by being unconscious. If you are part of that set then you don't get a save against any spell.
If you are conscious then you get to make your choice whether to be part of the willing targets set whenever you want (and people can be assumed to default to being unwilling), if you are unconscious then you automatically become a willing target.
Willing is not something that only exists for specific spells, specific spells just restrict
you to only willing targets.