> "Free" in this case means no added monthly expense beyond the bare minimum
So "free" as in "ignoring actual costs" and "ignoring opportunity costs".
Storage needs can change quite a bit over time. Household sizes sometimes change over time. Hobbies can change. Lifestyles can change. What was more than enough storage space several years ago can become not enough later on. Buying a bigger house to have more "free" storage space isn't really "free", especially as interest rates have increased massively over the years.
For instance, in the past my needs for storage for "camping gear" was largely handled by a single big backpack. Its just me, I'm down for pretty light camping. Now I've got multiple different sized tents for different kinds of trips, a sun shade, a whole family's worth of camping chairs, folding tables, camping stoves, multiple lanterns, camping related toys and activities, far more water storage, etc. What was easily stashed in a corner of a closet is now practically its own shelving unit.