Thanks for the suggested read, sounds interesting indeed.

I'm not comparing simple vs. complex but rather sound vs. flawed, although often sound = simpler than flawed.

The 737 here is yet another example of this : - the MAX design is flawed : faulty risk assessment of MCAS, seemingly unstable airframe in some configurations - a likely sound design could be : airframe rework, thorough risk assessment, extra pilot training...

While the flawed design came at a lower initial cost, it will now overrun the cost of a likely sound one (further rework + retrofit + sales/reputation damage + legal), including the cost of a probable longer design phase in the latter.

(I concede that legal/sales costs are not directly technical debt costs).