That's precisely it, each to their own, everyone has different needs/requirements, you have to do what you feel is right for your business, the guy did say he lived in a flat so couldn't fill up there, so for him a small unit 'lockup' is an essential part of his biz.
Likewise for me, I can not keep 5 vans on the drive or on the street I also can not put that money towards a place to own, so catch 22 I have to have a unit.
It's great if you can park one or two vans at home, I'd say do that for as long as it's reasonable possible.
But sometimes a growing biz needs a commercial unit
Darran