I mean, after all, in the real world, there is a HUGE difference between 4 inches and 4 feet. Even more so between 4 feet and 4 miles!
It's been a fight throughout the years to get a lot of the kids to understand this. The mentality seems to be that as long as the number is correct, that's all you really need. They're shocked (and often angered/annoyed) when I tell them that an answer of 12, 35, or 2,453 is flat out wrong and that the number means nothing without the unit. (And now throw in squared and cubic to change the "flavor" of the unit)
I'll admit, I do take a kind of devious pleasure in walking around the room and telling kids who have the right number but no unit, "Sorry... You're close, but that's not it." Then giving a thumbs up to a kid at the same table who has the right number and unit. It's kind of fun to see the first kid glance at the other child's paper, see the same number, and go from confused to indignant, to understanding.
I'm just afraid that some of these kids, when the grow up, are going to be very upset when they design their dream home and go to find a very lovely doghouse.