Raymott: But if most people decide that the subjunctive is no longer necessary...
Regrettably, this was not an informed decision, nor indeed, a 'decision' at all;
more a circumstance born of (for whatever reason) not knowing any better, and of copying what they hear.
Well, I don't think we know whether it's a conscious decision or not. I'm not even sure who wrote the song. Generally speaking, I know university lecturers who consciously do not use the subjunctive in this case.
As I understand, most posters to this forum are asking quite definitely for the 'correct' ways in which to express themselves, and with the rules of grammar as the standard and in the interests of preserving the subtleties of clear expression, I will be supporting Jlinger's stance.
I've already agreed that an extreme prescriptivist would take this view.
And I've agreed that, in theory, it is correct.