Membrane keyboards are so incredibly common and simple to make that I'd be willing to bet they make dramatically more profit on that keyboard than on a $1500 laptop (proportional to price). Even after accounting for all the wasted R&D and refunds and repairs spent denying problems with their butterfly mechanism.
So kinda yes... but also kinda no, I don't think that really supports a claim that it's cheap enough to do everywhere.
But yeah, I'd totally be fine with an LED glued into a hole. The indicator is the important part, and it's a shame that it's gone.
And a hole with a plastic insert would be fine for me too. It wouldn't be as minimalist but not doing it at all is much worse IMO.