Your anecdote is hilarious. But so true!
We aren't at peak mindfulness yet:
https://trends.google.com/trends/explore?date=all&q=mindfuln...
However I suspect that the early adopters have moved on and the people preaching mindfulness are not the same sort of people as those that have moved on from it. We are in 'Eternal September' and 'Who ruined Burning Man' territory.
Those that are actually 'mindful' and can 'do it' would probably never think they were being 'mindful', would not be going to the classes or even doing the formal meditation. Instead of plucking a raisin and focusing on how it fits in their navel they are more likely to be walking the dog with smile for friends they see en-route.
It is the same with Buddhism. Those that are first to claim to be in to it are highly unlikely to be in an way Buddhist. Their neighbour who happens to do a few things for a few people and help others out financially is far more likely to make the grade. You don't brag about being Buddhist, it is not how it works. But 'Buddhists' do.
It is like those people that insist on being called a grand title that they haven't necessarily earned. If 'a lady' insists on being referred to as 'a lady' then she probably isn't. Mindfulness is one of those things where 'mindful' people probably almost certainly aren't. The universe works this way.
A thing to watch for is that the topic of 'mindfulness' can be discussed ad-nauseum as per creationism. Anyone who hates it is going to be somewhat less than mindful about those deep in the cult. Equally those caught up by the fad are going to be going deeply un-mindful when it comes to chastising those that call the whole thing bogus.
The catch to this is that there is a bigger picture. Right now we don't have a lot of useful political involvement in the West, for instance the new UK leader was selected by 0.1% of the population, with them being very much drawn from the 1%. So we have these fairly insane politicians running the show whilst the mindful crew are telling people to do things with raisins. Exactly as per your anecdote.
The creationism idea was a deliberate 'wedge strategy' to get people talking about something silly whilst funding for serious science is whittled away. Who knows, but maybe some Heritage Foundation is behind 'mindfulness' with it being Wedge Strategy for containing dissent.
I think the analogy of the camera phone is useful for understanding these things. Cameras can default to point to the outside world or to point the other way, at the self. If you have the camera pointing at the self rather than the world then you aren't going to see the world but the world might see (and like) you. We are culturally okay with people who only post pictures of themselves, we idolise them as rock stars.
There is also a low barrier to entry when it comes to 'mindfulness'. Compared to learing something real - e.g. playing a musical instrument, speaking a foreign language, writing code in object oriented modules, being good at a sport, 'mindfulness' is pretty easy. You can't pretend to be fastest doing the local sport run, you have got to actually do it. Mindfulness is not something objective like that.