> Have today's engineers somehow stopped believing that the simpler thing is the most useful?

Simplicity is a means to an end. There's no point in a "simpler" solution if it's more expensive and harder to maintain.

> Or is it that writing some code to glue together off-the-shelf parts is cheaper and easier than designing and manufacturing a giant machine?

Exactly.

Good engineering is about meeting the client's needs, not about showing off your own virtuosity. Too many on HN seem to forget that.