I really don't get why they left the light off them. It's not something that takes any space at all and they can even make it invisible when off with their micro holes like they did with the old Bluetooth keyboard.
Sometimes it seems Apple is just minimalist for the sake of it. Because this is really a useful feature.
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.