I'm going to suggest that a lot of this is your personal preference, and without more data (which presumably Google has) it's not fair to be so critical. Google does periodically ask "how did you like your trip?" so they're collecting the information.
I personally like the small side roads. I happily take alternative routes and saving time is just a bonus. Taking a wild guess, I would bet that majority of the population likes the alternative routing - either because they like the road less traveled or they're impatient and actually care about 3 minutes.
Majority can be good for helping decide defaults but it's a horrible metric to declare it must always behave like so. Particularly when the majority are in a minority of at least one of the choices, which I strongly suspect would be the case here.
I personally like the small side roads. I happily take alternative routes and saving time is just a bonus. Taking a wild guess, I would bet that majority of the population likes the alternative routing - either because they like the road less traveled or they're impatient and actually care about 3 minutes.