Bringing back vanilla

However, it had the wonderful effect of increasing beverage revenue for the airlines.

I'm pretty cynical but not that cynical. This has more to do with security theater. As you said the construction of a bomb of that type on an airplane was always far-fetched at best (I mean, have you seen the size of those lavatories? The idea that someone could turn that into a sophisticated bomb-making lab is utterly absurd). But security types are authoritarians, and always, always move in the direction of tighter restrictions, no matter how ridiculous. To roll them back now, even if it's the entirely sensible thing to do, would show weakness and they can't tolerate that. It's the new normal nowadays and, besides, careers are at stake. So we continue to take our shoes off and surrender 3.4oz bottles of sunscreen, all in the name of freedom.