All kinds of privacy concerns this could lead to as far as what the carpet home-base-database folks have at their disposal.
Suppose homebase knows all the homes with occupants that are progressively showing signs of getting fatter. They could sell that information to diet pill marketers.
You could also use this to identify other behavior patterns as well. If the subject tends to move from one room to the next more frequently one day, then it could imply that they're doing a lot of pacing because they're nervous about something going on in their lives, and so now they can sell that info to antidepressant marketers.
You could even use it for burglary detection. If floor activity is detected in front of a window without having shown any previous signs of walking around anywhere else in the house, you got yourself a window intrusion detection system. That could be a good thing, but of course, now the homeowner will be getting Brinks home security junk-mail.