I've found many "pure" breeds to be regrettably diminished, they look like the books say but they pay for it in some way. Shorter lifespans, health problems, mental problems, etc.
Out-crossing a purebred with something from a different style of dog can often produce much healthier pups than either parent. Great Danes and Collie make 3/4 sized, slightly skinny dane-like dogs that are shockingly robust and energetic and can live to 16+ in my experience (and that's as active working outdoor dogs).
How would they fare as indoor, backyard dogs taken for twice daily sedate walks though?
My personal (probably unpopular) opinion is that a lot of inner city people should not have the dogs they have - who need to be able to run around at all times, not just waste away.
It's also why I don't have a dog, for exactly this reason - I don't live in the country, with enough free space around.
I share your unpopular opinion and raise you that plenty of suburban families have dogs that waste away in yards when they really would benefit from walks or hikes.
Out-crossing a purebred with something from a different style of dog can often produce much healthier pups than either parent. Great Danes and Collie make 3/4 sized, slightly skinny dane-like dogs that are shockingly robust and energetic and can live to 16+ in my experience (and that's as active working outdoor dogs).