It is not the size of things like labs, rotties, german shepherds etc that precludes them from low maintenance/small space living it is their temperament and innate needs. Great danes, greyhounds etc can live in apartments/townhouses due to most of them not requiring a great deal of constant stimulation, whereas the 'working' breeds were bred like they are for a reason. We forget they are working animals, labs included. There are plenty of toy breeds that are low drive, happy to be in confined living and still be loyal and friendly. The wish to water down working breeds to suit modern expectations annoys me to no end ...Thats what I mean. A lot of people might like labs, but they are too big for an apartment or small house or similar. If there was a mini they would be able to still get their lab.
This is of course completely hypothetical, and is assuming that the exact same look and temperament were just in a much smaller package.
I'm happy with Malinois the way they are, but I would love to try some breeds we don't have here in Australia like the Presa Canario and Tosa Inu