For fear of of sounding like an in-my-day curmudgeon, are DMs these days just too lazy to make the game their own?
Yes. And you see that everywhere, not only in the increased demand of adventures but also on the constant cries for simplification, the complains about easy to understand 3 sentence rules and the demand for shorter and shorter combat (usually the rules heaviest part of D&D). I also think that things like "fail forward" is a symptom of this laziness as people do not want find other ways to succeed once their original thought out plan is blocked. Instead just continue like normal and add en extra encounter later on.
But to be fair, its not only the DMs who got lazy.