I've noticed that Google Maps has started sucking a lot lately, routing us onto routes that take 2-4 minutes longer when a faster route is clearly available or taking us on nonsensical detours, and I wonder if this experiment is a reason why.

There's a hidden cost to this, and that's trust in the mapping app. I've stopped using Google Navigation for routine trips where I know how to get to the destination. It used to be worth it for the traffic information, but now that there's a good chance that it'll take you on a slower route for reasons that may be beneficial to Google but detrimental to you, it's not worth it. My brother-in-law switched to Apple Maps for similar reasons: he's finding it simply gives better results nowadays.